SCOPE NEWSLETTER

NUMBER TWENTY PIVE

AUSTRALIA p.2

DARLING RIVER ALGAL BLOOMS A three year project was carried out in the Darling River at Bourke, the geographical centre of the well-documented 1991 algal bloom. The purpose was to study whether nutrients or other factors were limiting algal growth

AUSTRALIA p.2

THE CATCHMENT MANAGEMENT SUPPORT SYSTEM (CMSS) - A PILOT STUDY IN THE MURRUMBIDGEE CMSS, a decision support system, was developed for the Murrumbidgee catchment, (81 948km2). The simple computer program needs neither a technical nor computing background to set-up. This pilot study demonstrated the application of the system to a specifie area as an initial phase prior to its application to major catchments in New South Wales.

IRELAND p.3

PHOSPHORUS LOSS FROM SOIL TO WATER This book, published following an international workshop, provides a valuable reference resource on the state of knowledge of both pathways and mechanisms associated with phosphorus !osses from field and catchments.

UNITED KINGDOM p.4

PRECISION F ARMING FOR FERTILISER APPLICATION POLICIES This paper reviews the utilisation of fertilisers in precision farming as part of an integrated management system. The distinguishing factor is the acknowledgement that significant variability exists not only between fields but also within them.

DECEMBER 1997

ITALY p.S

ALTERNATING AEROBIC AND ANAEROBIC CONDITIONS TO INCREASE PHOSPHATE REMOVAL FROM W ASTEWATER Traditional wastewater treatment plants do not exceed P efficiencies of 30%. The Phostrip, Bardenpho and A/0 processes, recently developed and implemented in sewage plants have substantially improved this P recovery. This paper, focusing on A/0, describes the optimisation of this process in a laboratory­scaled single basin, by alternating sequences of aerobic and anaerobie phases.

NETHERLANDS p.6

HIGH NUTRIENT REMO V AL IN THE

THREE-SLUDGE SEWAGE TREATMENT This three stage concept combines a high­loaded activated sludge plant plus a settler for the biological removal of P, with two biofilm reactors for nitrification and denitrification (by adding a carbon source). A pilot unit (2-3p.e.) showed that sufficient residence time for bacteria activity was critical in P removal (to lmg/1) but that N reactors were relatively flow insensitive. A patent is pending.

INTERNATIONAL p.7

SECONDARY SETTLING TANKS Over the last 25 years the adverse effect of wastewater discharges on the aquatic environment has led to stringent legislation controlling treatment plant outputs. This International Association on Water Quality (IA WQ) report concentrates on improved activated sludge systems and the need to back this treatment stage with a weil designed SST thereby ensuring effluent quality under fluctuating influent quality and quantity conditions.

SCOPE NEWSLETTER

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AUSTRALIA

DARLING RIVER ALGAL BLOOMS

The National Resource Management Centre (NRMS) has recently finished a three year project in the Darling River at Bourke, the geographical centre of the well-documented 1991 algal bloom. The purpose was to study whether nutrients or other factors were limiting algal growth.

The Vollenweider model, developed from European and N.American research, was initially used to study a series of weir pools connected by short riverine stretches. It was found that Chlorophyll-a concentrations v. total P loading did not match levels predicted by the model developed for deep lakes, and in a riverine context can only be considered as indicative. So, what is limiting algal growth in the Darling River?

This has led to the development of two hypotheses: • "algal growth is limited by nutrient

availability ". • "the light climate in the Darling River is usually inadequate for algal photosynthesis and hence light availability controls al gal growth ".

In the first hypothesis, TN:TP ratios were at first determined - sorne of the 8 samples were found to be N limited, whilst others were P limited.

However, use of TN:TP ratios in Australian conditions is limited, as not all N or P is bioavailable. Often a very small amount of total P is in the nominally dissolved fraction ( < 0.003JLm). This is known as filterable reactive phosphorus (FRP) and is assumed to be the most readily bioavailable. Total N is

also divided into readily bioavailable DIN (dissolved inorganic nitrogen), the less assimilable organic nitrogen compounds, and particulate-bound N.

A study of the readily bioavailable nutrients (DIN:FRP) showed that (as later confirmed in a bioassays experiment in a field laboratory) ail 6 samples tested suggested nitrogen limitation.

However, these methods do not determine possible limitation at the time of sampling. ln situ measurements to determine the instantaneous physiological response in the algal cell to nutrient spike using Nutrient Induced Fluorescence Transient ("NIFT") assays showed that 2 of 8 samples were nutrient limited and both of these demonstrated N deficiency. The authors conclude that these conditions can provide a competitive advantage to cyanobacteria, which can fix atmospheric nitrogen and are not dependent on water-born DIN.

In the case of the second hypothesis, it was found that turbidity at Bourke was clearly related to flow regime during the study period (median turbidity 250 NTU). The analysis of the 2 longest "no water flow" periods since 1945 in '94 and '95 demonstrated that it is a combination of water column stratification and increased light penetration due to decreased turbidity that provides a dramatically improved light climate for algal photosynthesis. However, even if turbidity was normally less than 40 NTU during the large A. Circinalis bloom in 1991, it was found that extended periods of low turbidity were not the only influencing factor in excessive algal growth for turbidities have often been �40 NTU without the development of large blooms.

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SCOPE NEWSLETTER � --------

T o conclude, if there is indeed sufficient bioavailable phosphorus in the Darling River for an algal bloom to occur at any time, it is the imbalance between the consumption of the FRP by the alg�e and the slow rate of its resupply stemming from the sediments, that actually limit eventual algal biomass. This re­supply can be further retarded by manipulating nver flows to prevent stratification. MR. Grace, Mraci, B. T.Hart, Fraci, R.L. Oliver & C.M.Rees. Chemistry in Australia, August 1997, Vol. 64, N°7,pp 2-5

AUSTRALIA

THE CATCHMENT MANAGEMENT SUPPORT SYSTEM (CMSS)- A PILOT

STUDY IN THE MURRUMBIDGEE

CMSS, a decision support system, was developed for the Murrumbidgee Catchment, an area of 81 948km2, within the Murray Darling Basin. The simple computer program does not need a technical or computing background to set­up. This pilot study demonstrated the application of the system to a specifie area as an initial phase prior to its application to major catchments in New South Wales.

The area covers several large population centres and much of the intensive farming involves irrigated agriculture.

The system needs carefully collected and accurate information. Four key sets of data are required: • land use data • mapped land attributes • expert assessment of nutrient generation

rates • land use and land management practices.

CMSS can thus be used to assess the impact of nutrient loading from changes in land use and management practices. The system stores the quality of the information and can indicate any gaps in the information as weil as reliability of outputs.

Although data demands are minimal, collection of the data was time consuming due to the size of the area. 53 subcatchments, each with 20-99 mapping units, were identified. Shortcomings included the absence of an instream nutrient assimilation component and nutrient bio-availability factors.

CMSS includes a policy module - it accepts and analyses land use and management "policy" statements. It also includes a predictive model component involving a simple nutrient balance madel - thus it can calculate likely nutrient loads given a particular land use pattern and set of generation rates.

Land use data was extended to register point sources - sewage treatment plants, piggeries and fish farms.

Nutrient loads were calculated using '93 conditions- 3 400±595 tonnes total P and 26 000±4 500 tonnes total N. Overall, average total P and N generated is 0.4±0.1 kg ha-l year·l and 3.2±0.5 kg ha-l year-1 respectively. The land use contributions showed that 95% of nutrients are generated by diffuse source and only 5% by point sources. Dry land cropping, unimproved and improved pasture generate 80% of all nutrient loads; sewage treatment plants generate only 4%.

3

These results highlight the need to focus on certain parts of the catchment and consider the use of buffer strips etc. to reduce diffuse nutrient source inputs. CMSS has been incorporated into the NSW Algal Management Strategy and implemented in many NSW catchments. The Murrumbidgee CMSS is now being revisited to prepare its catchment nutrient management plan. S. Cuddy, B. Young, R.Davis & Trevor Farley .

. Managing Algal Blooms, Ch.9, pp. 103-113, 1997 ISBN 0 643 060499.

IRE.LAND

PHOSPHORUS LOSS FROM SOIL TO WATER

This book, published following an international workshop held at T eagasc, Wexford, Ireland in September 1995. It provides a valuable reference resource on the state of knowledge of both pathways and mechanisms associated with phosphorus losses from field and catchment.

Participants from over 20 countries established a new and more detailed understanding of the fate of P in agriculture and its contribution to the aquatic load. There is a growing appreciation that sewage works point source control alone will not resolve the P input issue and that agriculture has a major role to play. Diffuse farmland pathways and mechanisms were explored and, where data was available, qualified and quantified.

In addition to an 18 chapter comprehensive review, 45 posters are presented in the tex:t.

This publication should form the basis for the development of workable strategies for controlling agricultural P !osses and reducing or completely preventing this potential contribution to eutrophication. H Tunney O. T.Carton, P.C.Brookes & A.E. johnston. 468p., CAN International Publishing, 1997, ISBN 0 85199 156 4.

UNITED KINGDOM

PRECISION FARMING FOR FERTILISER APPLICATION POLICIES

This paper reviews the utilisation of fertilisers in precision farming as part of an integrated management system. Calculation of standard fertiliser recommendations for a particular crop is based on factors such as soil type, crop yield, fate of crop residue etc. Guidance is given on a field by field basis. The distinguishing factor in precision farming is the acknowledgement that sig nificant variability exists not only between fields but also within them.

Precision farming has been made possible through the use of new technologies. Automated techniques, using soil sampling and yield maps , have been developed allowing only the necessary amount of fertiliser to be placed on the land,. A series of experiments has been used to establish sampling procedures providing results with an acceptably low level of variance.

At such a level of precision critical levels of nutrients can be defined to limit runoff and leaching.

The Differentiai Global Positioning System (DGPS) is the US developed location system,

4

SCOPE NEWSLE_TIER __ � -�-�--

adopted from the Global Positioning System (24 earth satellites) and used for precision farming. DGPS receivers can be mounted on harvesters, sprayers or spreaders, or used as hand held units and give positions in real time.

Different types of fertiliser spreaders are available. These already have the facility for automatic rate control and severa! can be controlled by the combined use of a predetermined application map/ plan and the GPS receiver.

The yield map is essential to a fertiliser plan which needs to relate the real inputs of phosphate, potash and magnesium to the quantities removed in the harvested crop. The key to precision farming is the generation of a within-the-field yield map.

The paper concludes that precision farming relies on measurement and that the current lack of collected reliable data, due to the degree of manual input required, is a major constraint. The development of suitable sensors will lead to the development of more robust models for fertiliser recommendations. In future, variation in quality will become as important as variation in yield. Finally, environmental benefits will ultimately play an important role but will need to be quantified in order to give the needed impetus to this new technique. C.J.Dawson. The Fertiliser Society, Proceedings N°391, December 1996 ISBN 0 85310 0241.

ITAL Y

ALTERNA TING AEROBIC AND ANAEROBie CONDITIONS TO

INCREASE PHOSPHATE REMOVAL FROM WASTEWATER

Traditional wastewater treatment plants do not exceed P efficiencies of 30%. The Phostrip, Bardenpho and A/ 0 processes, recently developed and implemented in sewage plants have substantially improved this P recovery. This paper, focusing on A/0, describes the o ptimisation of this process in a laboratory-scaled single basin, by alternating sequences of aerobic and anaerobie phases.

Generally phosphorus is removed through thickened sludge, with an efficiency of -30%. The remaining phosphorus is then removed using chemical additives, thereby adding to costs. High phosphorus content in the sludge makes it more suitable as fertiliser when agricultural spreading is permitted.

In this study anaerobie conditions lasting 15h were alternated with aerobic conditions of 9h duration. A synthetic wastewater was used following inoculation of an activated sludge (enriched with Acinetobacter spp) from the municipal treatment plant in Puntavagno, Genoa.

Results incorporated a residence time in arder to allow biomass to adapt to high phosphorus levels. The process studied reduced the start-up time from 30 to 20 days, stabilised removal yield to 90% and prevented wash-out of suspended solids. It was concluded that the biomass fraction, which was unable to adapt to high phosphorus levels, becomes progressively eliminated. Results of continuous

5

phosphorus removal runs at 4 different feed phosphate concentrations (i.e. 18, 36, 68 &

100mg/l) show that P-accumulating rnicroflora are able to completely metabolise phosphate as polyphosphate up to an influent phosphores concentration of -SOmg/1. For P influent > SOmg/1, phosphate removal yield eventually decreases up to 85%. Over 90mg/l the system tolerates phosphorus overload for no more than 10 days, after which the yield falls to zero.

The paper concludes that fixed and operational costs appear substantially lower due to the elimination of the separate aerobic vessel and by lirniting aeration to only 40% of process time. CSommariva, A. Converti & M.Del Borghi. Rej Desalination, 108, (1996} pp25 5-260.

NETHERLANDS

HIGH NUTRIENT REMOV AL IN THE THREE-SLUDGE SEWAGE

TREATMENT

This three stage concept combined a high­loaded activated sludge plant plus a settler for the biological removal of P, with two biofilm reactors for nitrification and denitrification. A pilot unit (2-3p.e.) showed that sufficient residence time for bacteria activity was critical in P removal (to lmg/1) but that N reactors were relatively flow insensitive. A patent is pending.

The aim of this research carried out at Wageningen Agricultural University was to: • determine maximum hydraulic load

• determine the effect of hydraulic peak loads • evaluate economie prospects of the system

The pilot plant, for 2 to 3 p.e., was fed with raw domestic sewage. The hydraulic load of the plant was increased regularly and thus the hydraulic residence time (HRT) decreased. Real-life conditions were duplicated. Both the influent and effluent of each bioreactor were continuously sampled and, twice a week, on every third and fourth day, composite samples were analysed. The experiment was divided into 2 periods, each of 14 weeks.

Increasing hydraulic 1oad, and thus decreasing HR T decreased the remo val efficiency of the dephosphatating stage, although removal efficiencies remained stable in the second and third reactors. This implied that the first stage could be a limiting factor in this new concept.

The required effluent standards for N total and P total were easily achieved (respectively 10mgN/1 and lmgP/1). It was surprising to note that the concentration of suspended solids remained low (3mg/l), probably due to the filtration capacity of the carrier materials in the biofilm reactors. Total HRT was 10.4hrs, compared to 20hrs in conventional WWTPs.

Rainfall and day/night effects led to dramatic changes in the influent flow rate - during rainfall removal efficiency was satisfactory in the first period (2.5 times dry-weather flow) but in the second (3 times dry-weather flow) it decreased with the final mean proceeding effluent concentration P-total at 1.8mg/l. However, high concentrations of P input (up to 25mg/l) were removed to a level lower than 2mg/l after passing through the 3 reactors, even during rainfall. This proves the system's good removal capacities. The system was also found to be very flexible since the biomass easily recovered from peak loads.

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SCOPE NEWSLETTER

Investment costs are lower or comparable to those of an ultra-low-loaded activated sludge plant. Operating costs are comparable and, moreover, this new technology could be a very interesting alternative if required space is considered ( only about a third of the size of a conventional sytem for 100 000 p.e.). Costs of controlling odour problems were relatively low.

The next phase of the research is to scale up the system to a semi-technical scale (500 p.e.), focusing on removal efficiency and stability at full scale conditions. The final goal would be fully-sized operating plant in the near future. E.H.Marsman, P.].Roeleveld & J.HRensink Ref. Wat. Sei. Tech. Vol. 35, N°10, pp129-136, 1997.

INTERNATIONAL

SECONDARY SETTLING TANKS (SSTs) THEORY, MODELLING,

DESIGN AND OPERATION

Over the last 25 years the adverse effect of wastewater discharges on the aquatic environment has led to stringent legislation controlling treatment plant outputs. This International Association on Water Quality (lA WQ) report concentrates on improved activated sludge systems and the need to back-this treatment stage with a weil designed SST thereby ensuring effluent quality under fluctuating influent quality and quantity conditions.

This up-to-date manual covers international developments in SST design, practice and research since the 1970's. The targeted audience are principally engineers and

scientists involved in the design and operation of activated sludge WWTPs.

Activated sludge systems have been extended from organic carbon removal, to include N removal by nitrification and denitrification, as weil as the removal of phosphates. The configuration of the system has, as a consequence, increased in complexity and the number of physical, biological and chemical processes and substances influencing effluent quality has expanded.

The SST plays a major role in achieving the increasingly demanding quality standards for ensuring the efficient "capture" of SS. At many WWTPs, improvements in effluent COD (BODs), total N and total P can only be achieved by reducing effluent SS concentrations. This can often be accomplished without the additional cost of effluent filtration through the simple improvement of SST design and operation in general and, in particular, by incorporating improved flocculation features. G.A.Ekama, J.L.Barnard, F. W Günthert, P.Krebs, f.A.McCorquodale, D.S.Parker &

E.J. Wahlberg. Scientific Technical Report (STR) N°6, lA WQ, ISBN 1 900222 03 5, ISSN 1025-0913, 1997.

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The SCOPE Newsletter is produced by the CENTRE EUROPEEN D'ETUDES DES POL YPHOSPHA TES, the phosphate industry's research foundation and a sector.group of CEFIC (The European Chemicallndustry Council).

The SCOPE Newsletter seeks to promote a better understanding of the sustainable use of phosphate and the rôle of phosphate in the Environment

The SCOPE Newsletter is open to input from its readers and we welcome ali comments or information. Contributions from readers are invited on ali subjects concerning phosphates, detergents, sewage treatment and the environment. Y ou are invited to submit scientific papers for resume or full publication, to send comments on the studies mentioned in this Newsletter or other scientific or technical views:

For more information, please contact : .

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SCOPE NEWSLETTER

NUMBER TWENTY FOUR

THE NETHERLANDS p.2

THE METABOUSM OF MICRO-ORGANISMS RESPONSIBLE FOR PHOSPHORUS REMO V AL Micro-organisms, which are able to accumulate phosphorus as polyphosphate inside the cell, are widely used in enhanced biological phosphorus removal from wastewater. No pure culture, having the same characteristics, has yet been isolated. This paper shows that it is possible to use enrichment, as opposed to pure cultures, to understand, on a metabolic level, the complex dynamic stoichiometric and kinetic microbial mechanisms.

SWEDEN p.3

HUMAN WASTE RECYCLING Human urine alone contains over 80% of the nitrogen and 60% of the phosphorus in household wastewater; furthermore it has very low levels of heavy metals. This report studies the practicalities of a urine collection system in a Swedish eco-village in order to recycle the urine for agricultural purposes, as a fertiliser; thus human waste can become a resource rather than a pollutant.

UNITED K.INGDOM p.3

EVALUATION OF METHODS USED TO DETERMINE TOP IN SOIL SOLUTIONS Due to a growing awareness of the significance of

· phosphorus transfer to water across soil boundaries, a simple, high quality method to monitor the movement of total dissolved phosphorus (TDP) is necessary. Analysis can be problematic due to trace concentrations of P in the presence of higher concentrations of a number of organic and colloïdal fractions This paper evaluates a number of methods used to determine TDP using leachate water from lysimeters with 10 different UK soil types. A final recommendation is made.

AUSTRALIA

THE FILTER TECHNIQUE FOR EFFLUENT TREATMENT - PART 2

p.4

SEWAGE

This report covers the planned trial application of the FIL TER (Filtration & Irrigated cropping for Land Treatment & Effluent Reuse) technique in the Murray River Basin - first referred to in Newsletter 20. A 16 hectare pilot trial area is being leveled into irrigation hays to receive effluent from the Griffith Sewage Works.

OCTOBER 1997

DENMARK p.S

ALGAL BIOMASS REGULATION IN A SMALL LOWLAND STREAM The role of invertebrate grazing, phosphorus concentration and irradiance in the regulation of benthic algal biomass on stones (sorne of which were treated with insecticide) were studied in a 3 year field experiment in a small Danish lowland stream.

GERMANY p.6

DAMMING OF THE DANUBE - EFFECTS ON BLACK SEA BIOGEOCHEMISTRY Although damming is known to affect riverbourne nutrient loads and their ecosystems, effects in open coastal waters are less certain. ln this report long term water and nutrient data from the River Danube to the Black Sea is presented. A decrease of two-thirds in the load of dissolved silicate in the river is revealed, with a corresponding shift in phytoplank.ton species away from diatoms.

LONG TERM RECORDS IN LAKE MENDOTA Mean Secchi disk readings, covering the six seasonal periods for a large part of this century, plus other data, were used to assess the effects of nutrients and herbivory on water clarity in Lake Mendota, (3985ha, 25.3m max. depth).

FINLAND p.7

EFFICIENCY OF PHOSPHATE AND ZEOUTE BASED WASHING POWDERS This study was undertaken to determine if phosphate and zeolite based detergent powders with differing physical properties were equally efficient at removing dirt under similar washing conditions.

SCOTLAND

PROCEEDINGS CONFERENCE

FROM p.8

EDINBURGH

The 1995 Edinburgh Conference, organized by the Scottish Environment Protection Agency, brought together agriculturists, scientific advisors, water pollution scientists and focused on issues relating to diffuse pollution from agriculture.- nitrates, phosphorus, pesticides plus the nature and effectiveness of the regulatory regime. A

collection of the pa pers presented has been published.

THE METABOLISM OF MICRO-ORGANISMS RESPONSIBLE FOR PHOSPHORUS REMOVAL

Micro-organisms, which are able to accumulate phosphorus as polyphosphate inside the cell, are widely used in enhanced biological phosphorus removal from wastewater; the competitive advantage being their ability to use polyphosphate as an energy source for the uptake and storage of acetic acid. No pure culture, having these characteristics, has yet been isolated. This paper shows that it is possible to use enrichment, as opposed to pure cultures, to understand, on a metabolic level, the complex dynamic stoichiometric and kinetic microbial mechanisms.

The difficulty in obtaining a pure culture is due to the fact that enrichment procedures used are static. The organisms involved have a strong competitive advantage due to their ability to adapt to highly dynamic conditions. The theory, based around Phosphate Accumulating Organisms (PAO), was sufficient to empirically design and operate processes - but lack of knowledge means trial and error procedures are used in process designs, and causes of disturbance are difficult to detect. No pure culture has yet been reported to have the full range of characteristics equivalent to the behaviour of polyphosphate organisms in activated sludge.

Cultures enriched in the laboratory were used in the most successful studies. Sludge is exposed to anaerobie and aerobic conditions in sequencing batch reactors (SBR), with acetic acid only present during anaerobie periods thereby allowing growth of only those organisms capable of metabolising acetate in the absence of electron acceptors.

Stoichiometric coupling between ortho-phosphate release and acetate uptake under anaerobie conditions was noted in early studies. The organisms do not accumulate phosphate when substrate and electron acceptors are present - this could be the

vital indicator as to why the 'real' phosphorus removal organism has never been enriched. A metabolic model able to describe conversion rates of all components involved in the process was developed. The main difference between oxygen and nitrate as an electron acceptor is the different efficiency of oxidative phosphorylation. The parameters necessary in a metabolic model are fewer than for a black box model. Model predictions were coherent with experimental results and mass balances over each experiment were closed, indicating that all components of the process are known and that the metabolism of the organisms could be described in terms of stoichiometrics and kinetics.

Storage polymers play an important role in natural ecosystems, which rarely have constant supplies of electron acceptors. There is a need to develop these dynamic selective enrichment techniques in the context of both microbial ecology and new processes in environmental biotechnology. For instance, substrate accumulation by micro-organisms of organic compounds from dilute waste flows could allow for these compounds to be reused ( eg : methane gas digestion). M CM. Van Loosdrecht, G.JSmolders, T.Kuba & JJHeijnen. Ref.: Antonie van Leeuwenhoek 71: 109· 116, 1997.

HUMAN WASTE RECYCLING

Human urine alone contains over 80% of the nitrogen and 60% of the phosphorus in household wastewater; furthermore it bas very low levels of heavy metals. This report studies the practicalities of a urine collection system in a Swedish eco-village in order to recycle the urine to agriculture as a fertiliser; thus human waste can become a resource rather than a pollutant.

The toilets used were equipped with two bowls, for the separate collection of urine and faecal material, and with two separate flushing systems, requiring only a small volume of water to be flushed. The

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SCOPE NEWSLETTER

urine was piped to a collection tank, followed by a storage tank where it was sanitised and consequently

used as fertiliser for cereal crops. The source separation of urine can be added to any sewage system.

The purpose of the study was to measure the quantities of nutrients per person, daily, separated into the urine fraction, as weil as the collection of heavy metals and faecal contamination in the collection system. The urine solution was analysed chemically each time to study how rapidly the urea dissociated to ammonium and carbon dioxide. The experiment was carried out in Understen eco-village on 44 apartments, 160 persons, during two consecutive 14 day periods. Each inhabitant filled in a form relating collection of urine, heavy metals and nutrients to the amount of time they spent at home (average 13.9 hrs per day). They were also asked if they were vegetarians (10%). The proportion of children (2-13 yr.) in this study was higher than in Sweden as a whole.

All factors considered, quantities of nutrients were close to those expected, indicating that 80-100% of the urine generated was correctly separated .. Dissociation of urea in the collection pipes was rapid, activated by the biofilm layer lining the pipes. A high proportion of nitrogen in urine is stored in the form of ammonium/ ammonia and the pH-value, due to dissociation was high (9) - thus ventilation of the tank and collection pipes should be restricted to avoid ammonia emissions and losses. The urine contained _3.2 mg cadmium/kg phosphorus, a very low level compared to chemical fertilisers C26 mg Cd/kg P) and sewage sludge (NSS mg Cd/kg P). Contamination with faecal material was low C 1mg faecal material/1 urine solution) and flush water usage was diminished by 50 %. Source urine was thus considered to compare favourably with mineral fertilisers and other organic fertilisers of urban origin (eg. compost). H]onsson, T.A.Stenstrom, ].Svensson and A.Sundin. Ref Wat. Sei. Tech. Vo/.35, N°9 pp, 145-152, 1997.

EVALUATION OF METHODS USED TO DETERMINE TOP IN SOIL SOLUTIONS

Due to a growing awareness of the significance of phosphorus transfer to water across soil boundaries, a simple, high quality method to monitor the movement of total dissolved phosphorus (TOP) is necessary. Analysis can be problematic due to trace concentrations of P in the presence of higher concentrations of a number of organic and colloïdal fractions. This paper evaluates a number of methods used to determine TOP using leachate water from lysimeters with 10 different UK soil types. A final recommendation is made.

The study focused on the determination of TDP, passing through the 0.45 p.m filter, including inorganic, organic and P attached to colloïdal material. This determination allowed the difference between TDP and molybdate reactive P (MRP) to quantify dissolved, unreactive P in its various forms. Dissolved P in soil solution may also be important, contributing to eutrophication if mobilised to surface waters.

Soil was collected 7 days prior to analysis, from free­draining lysimeters at experimental sites, covering a range of different soil types, notably at: Great Dun Fell, Aber and North Wyke. Three methods were employed which used different digests with standard molybdate blue colorimetrie determination: mild digestion (persulfate), peroxide-Kjeldahl and nitric sulphuric acid. In a fourth method inductively coupled plasma-optical emission spectrometry (ICP­OES) was utilised. Aqueous solutions were prepared containing nominal concentrations (100 mg PL-1), and cooled to 4°C. On the day of analysis samples were prepared by 1000 fold to obtain a nominal concentration of 100 p.g PL-1. Each of the soil and synthetic solutions were replicated (n=S).

Soil solution concentrations of TDP were significantly different (P < 0.001) between methods. Eight of the ten soils contained MRP concentrations below 100 p.g L-1p_ AQUACHECK

3

{an interlaboratory sample exchange scheme) samples showed that data obtained by the ICP-OES method and persulfate methods were the most precise {%rsd=3%) but ICP-OES was not sensitive enough to use below 100 J.'g L-1 P·

The nitric acid-sulphuric acid digestion method was slow and required constant attention. Recoveries for model compounds were erratic; soi! solution was subject to high blank values and cross­contamination; poor reproducibility at trace concentrations was also a problem. These disadvantages highlighted the need for an alternative procedure for routine analysis.

In the peroxide-sulphuric acid digestion experiment AQUACHECK samples indicated that the method was not completely effective in recovering P. Overall the method was considered to be reasonably robust, although it was difficult to control the final stages to avoid superheating and volatilisation.

The persulphate digestion procedure, using sealed reaction vessels, was the mildest wet oxidation method evaluated. Advantages included control simplification plus reduced contamination compared with other methods, which use open vessels. The acidified · conditions are less oxidising than the alkaline alternative, thus potential oxidation and interference from Mn2

+ are avoided.

T o summarize, the most important factors in obtaining accurate ·and precise estimates of TDP were the sensitivity of the procedure, simplicity of oxidation conditions, plus the ability to control the reaction, thus avoiding contamination. On this basis the persulfate digestion method was recommended. A.P.Rowland & P.MHaygarth. jour. Environ. Quai. Vol. 26, N°2 pp.410-415, March-Apri/1997.

THE FILTER TECHNIQUE FOR SEWAGE EFFLUENT TREATMENT- PART 2

This report covers the planned trial application of the FIL TER (Filtration & Irrigated cropping for Land T reatment & Effluent Reuse) technique in the Murray River Basin in Australia - first referred to in Newsletter 20. A 16 hectare pilot trial area is being leveled into irrigation hays to receive effluent from the Griffith Sewage W orks.

The system was designed to reach EP A treated effluent targets by reducing phosphorus from 2-8 mgs/L to less than 1mg/L and nitrogen from 20mg/L to less than 15mg/L by 1999 in a sustainable, efficient way. Although systems using artificial wetlands, cropping and woodlots are gaining popularity, they are expensive in large urban centres, due to costs involved in storing excess effluent during periods when crop and pasture growth is low. In addition, on slowly permeable soils, such as those in Eastern Australia, waterlogging and salinisation often occur.

A system was proposed whereby crops are grown over a network of sub-surface drains, thus combining irrigated cropping with filtration of effluent through the soi! to a drainage system when cropping activity is low. The rate of sub-surface drainage could be regulated, ensuring sufficient nutrient removal and reaching target criteria.

Trials took place in 1994 (for details refer to Newsletter 20). Mean P concentrations feil by 98% to > O.Smg/L and N by 85% to > Smg/L. The applied effluent contained blue-green algae (Mycrocystis), whilst drainage waters were colourless and free of blue-green algae due to the increase in N:P ratio (as N:P falls below 12 so the risk of blue-green algae increases). Occurrence of downstream blooms was much less likely.

Other trials indicate the potential usage of the system to dean pesticide-contaminated run-off. Adapted versions of the system could be used to treat industrial and commercial effluent containing

4

SCOPE NEWSLETTER

chemicals and heavy metals, or management of salinity problems in irrigation regions.

Encouraged by the success of the trials to date, a year-long commercial scale trial is planned. The pilot system will cover 16 ha of farmland, and, if successful, will be extended to 130 ha. This would be sufficient to handle Griffith's (18 000 pop) sewage effluent in time to meet the EPA's 1999 deadline, whilst generating 1000T /yr of high quality grain and hay. B. Bennett. Ref.: Ecos, Winter 1997, pp 30-33.

ALGAL BIOMASS REGULATION IN A SMALL LOWLANDS�

The role of invertebrate grazing, phosphorus concentration and irradiance in the regulation of benthic algal biomass on stones (sorne of which were treated with insecticide) were studied in a three year field experiment in a small Danish lowland stream: Gelbaek stream in Jutland. Three experiments were carried out between March and August.

Inter-annual differences in peak-algal biomass were presumed to be due to differences in grazing pressure, with growth being further limited by a reduction in light from leaf vegetation proliferation on the banks in the summer. Three experiments were designed to determine:

• if invertebrate grazing in early spring could regulate algal biomass development

• if algal growth was phosphorus limited in spring • if a fall in light due to leaf proliferation could

limit algal growth thus determining the timing of peak biomass.

The invertebrate grazing experiment, conducted over 44 days in spring '92, used an aluminium frame, consisting of 4 troughs stocked with stones originating 20m upstream. Stones from two of the troughs were treated with an insecticide (Permethin). Nutrient concentrations were high (orthophosphate 33-117JLgl-1). Algal biomass was

found to be regulated by invertebrate grazing. It was found that invertebrate scrapers could regulate algal biomass accretion and suggested that A.jluviatilis was largely responsible for invertebrate grazing pressure. The density of this snail on untreated stones and stones treated with insecticide varied by 50 %. Algo-biomass increased significantly on the insecticide-treated stones.

The phosphorus enrichment experiment was conducted over 35 days in spring '91: an inorganic phosphorus solution, from a butt on the bank, was continuously added to 3 troughs, whilst 3 others served as controls. Algal biomass development on stones was not found to be phosphorus limited during the spring algal bloom, and th us could not be controlled by nutrient limitation.

The irradiance experiment was carried out over 70 days in summer '91: two reaches, one shaded and one not, were used, and stocked with non-colonised stones; 10 from each reach were sampled biweekly to monitor algal biomass and scraper density. A very low biomass accumulation occurred in the shaded reach, whilst a peak of 800mg chlorophyll m-2

occurred after 6 weeks in the non-shaded reach.

It was concluded that invertebrate grazing can prevent significant increases in algal biomass despite a surplus supply of nutrients. Reduced light conditions, either from an overhead canopy or self shading, also play a part in limiting algal biomass increase. Insecticides, it was shawn, may have the reverse effect of permitting algal growth due to reduced grazing input. Algal biomass regulation can be considered as a complex interaction of top-down and bottom-up mechanisms. K.Kjeldsen Ref.: Freshwater Biolog;y (1996} 36, 535-546.

5

DAMMING OF THE DANUBE- EFFECTS ON BLACK SEA BIOGEOCHEMISTRY

Although damming is known to affect riverbourne nutrient loads and their ecosystems, effects in open coastal waters are less certain. In this report long term water and nutrient data from the River Danube to the Black Sea is presented. A decrease of two-thirds in the load of dissolved silicate in the river, was revealed, with a corresponding shift in phytoplankton species away from diatoms, since dam constructions in the early '70s. Results show that the biogeochemistry of the entire Black Sea basin bas been altered.

Dams can reduce nutrient loads due to the removal of nutrients to reservoir sediments ('the anificial­lake effect ') . Although this removal could be compensated for by anthropogenic nitrogen and phosphorus inputs downstream, no such compensation has been observed for silicate. Median silicate concentration (58�-LM) in the Danube for the period 1979-92 is considerably lower than for the pre-construction period 1959- 60 (1401-LM). In winter, concentrations of silicate in coastal waters 1960-92 fell from 55�-LM to 20�-LM, after the dam was built. Nutrient concentrations on the coast were also influenced by the Danube - though nitrogen and phosphorus were only slightly affected by coastal sources. The dramatic fall in the Si:N ratio (42 to 2.8) can be accounted for by the increase in dissolved organic nitrogen from increased inputs from the Danube. This change in nutrient inputs has led to a dramatic shift away from diatoms to coccolithophores and flagellates (non-silica based): increases of a factor of 2.5 and 6 were noted respectively. It can be assumed that a large part of the increase in nitrogen loads after damming of the Danube are being, and will be, removed by non­diatom species. The effect of the decrease in silica was also observed in the Black Sea.

The occurrence of taxie flagellate blooms may become more widespread - to the central Black Sea -as observed in other coastal areas. Effects of altered

silicate inputs, overfishing plus the introduction of alien species, have yet to be studied.

Similar dam constructions world-wide (more than 36 000) should now be examined for their possible influence on food web structure in closed seas, lakes and rivers since these effects could be of global consequence. C.Humborg, V.Ittekkot, A. Cociasu & B. V.Bodungen. Ref.: Nature, Vol. 386, 27 March 1997, pp. 385-388.

LONG TERM MENDOTA

RECORDS IN LAKE

Mean Secchi disk readings, covering the six seasonal periods for a large part of this century, plus other data, were used to assess the effects of nutrients and herbivory on water darity in Lake Mendota, Wisconsin, (3985 ha, 25.3 m max. depth).

The control of phytoplankton blooms and the role nutrients and zooplankton play is not fully understood. This study seeks to understand if, in the long term, grazing can improve water clarity in a large eutrophie lake, at varying nutrient levels. The lake has a history of algal blooms since at least the late 1800s. It has been subject to increased phosphorus loading rates during this century.

Readings were divided into 6 seasonal periods distinguished by a number of precisely defined criteria. It was found that despite different nutrient­herbivory interactions the summer algal blooms had not increased since 1900. Water clarity was at its greatest from spring turnover through to autumn destratification, corresponding to the time when herbivory levels were high. Indications are that lake size and trophic status do not prevent lakes from achieving increased water clarity from biomanipulation that increases herbivory. Grazer effects on water clarity can be seen over a long period, and, in principle, there may be no time restriction on grazers' capacity to control phytoplankton. In practical terms, however, sustained biomanipulation may be problematic. The

6

SCOPE NEWSLETTER

authors conclude that management programmes involving P reduction and biomanipulation may be more effective than if only one technique is used on its own. R. C.Lathrop, S.R. Carpenter and L. G.Rudstram. Ref.: Can.]. Fish. Aquat. Sei 53:2250-2261. 1996.

EFFICIENCY OF PHOSPHATE AND ZEOLITE BASED W ASHING POWDERS

This study was undertaken to determine if phosphate and zeolite based detergent powders with differing physical properties were equally efficient at removing dirt under similar washing conditions.

Results were correlated in terms of whiteness, redness and blueness, as well as detergent residues in the materials and the washing machines.

Smaller particle zeolites-based detergents did not wash as well as larger particle detergents and the former lefi: more residue. New clothes with coarse fibres had the most residues.

It was found that phosphate based detergents lefi: significantly less residue and increasing the number of washes did not have any effect on the amount of phosphate residues lefi:. This discrepancy was all the more apparent when energy saving washing machines using less water and mechanical input were used.

Residues imply possible irritation and sensitivity for the user, which could be minimised by using phosphate-based detergent powders. HAino. Ref.: Master's Thesis, University of Helsinki, Faculty of Agriculture and Forestry, May 1997.

PROCEEDINGS CONFERENCE

FROM EDINBURGH

The 1995 Edinburgh Conference, "Diffuse Pollution and Agriculture", organised by the Scottish Environment Protection Agency, brought together agriculturists, scientific advisors, water pollution scientists and focused on issues relating to diffuse pollution from agriculture - nitrates, phosphorus, pesticides plus the nature and effectiveness of the regulatory regime. A collection of the papers presented has now been published.

These conference papers provide an up-to-date account, and a perceptive insight, into a growmg environmental problem in agriculture.

The presentation of the papers led to a good debate and the establishment of a strong rapport amongst participants. Emphasis was on future actions and it was agreed that research into practical solutions, co­operation at all levels and the formation of partnerships were the only way to bring about lasting change and improvement. Evidence of strong commitment to the debate has been witnessed since, through both follow-up research on nitrates, and the establishment of partnerships aimed at the application of new farming methods.

A follow-up regional conference is planned in 1997 ensuring that the original impact of this first conference was sustained. Edited by T.Petchey, B.D �rey and A.Frost, The ScottishAgricultural College, 1996, ISBN 1 85482

575 5.

7

The SCOPE Newsletter is produced by the CENTRE EUROPEEN D'ETUDES DES POLYPHOSPHATES, the phosphate industry's research association and a sector group of CEFIC (The European Chemical Industry Council).

The SCOPE Newsletter seeks to promote a better understanding of the sustainable use of phosphate and the role of phosphate in the Environment

The SCOPE Newsletter is open to input from its readers and we welcome ali comments or information. Contributions from readers are invited on ali subjects concerning phosphates, detergents, sewage treatment and the environment. Y ou are invited to submit scientific papers for resume or full publication, to send comments on the studies mentioned in this Newsletter or other scientific or technical views:

For more information, please contact : NEWTON CONSULTING NETWORK- who produce this SCOPE Newsletter-9, rue Newton, Paris, France, Tel : 33-1-53-57-7698 Fax 33-1-53-57-7679

e-mail : newton@newton-consulting.com

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NUMBER TWENTY THREE

THE NETHERLANDS p.2

SELECTIVE REMOVAL AND RECOVERY OF

PHOSPHATE USING A NEW CLASS OF SORBENTS­

II- PROCESS OPTIMISATION

The main processes conceming the precipitation of calcium phosphate in a fluidized bed were established (see Newsletter 22). An optimisation of the phosphate removal efficiency was attempted, in this second paper, by focusing on the aggregation process.

THE NETHERLANDS p.2

ENVIRONMENTAL IMPACTS OF NUTRIENT

REMO V AL PROCESSES

The influence of primary clarification of sewage on nitrogen

and phosphorus removal was studied, in a modified University of Cape Town type wastewater treatment plant (WWTP), using batch tests, on a full scale, before and after the introduction of raw sewage. Both the effect on the activated sludge population and the overall environmental impacts were studied.

THE NETHERLANDS p.3

EFFECTS OF ANIMAL W ASTE APPLICATION TO

SANDY SOILS ON DOP LEACHING

A substantial part of total P in soil solution and leachates can exist as dissolved organic phosphorus (DOP), which may be more mobile than inorganic orthophosphate and so be an important P source for surface water. eutrophication. The analysis of DOP has not been included in many field studies,

nor included in models developed to predict the movement of P through the soil. This paper focuses on four experiments to investigate the effects of pig waste application to sandy soil on DOP leaching.

INDIA p.4

RECLAMATION OF EUTROPHIC WATERS:

NUTRIENT REMOV AL BY WATERHY ACINTH

A vast number of tropical pond wetlands are no longer suitable for fish culture in India. Sophisticated ecotechnological models used for control of eutrophication in advanced countries are not suitable in the small, shallow ponds used for fish farming in developing countries. The use of biological agents is ecologically significant due to their ease of handling and as component members they may cause Jess perturbation. Nutrient removal capacity of waterhyacinth was studied.

SEPTEMBER 1997

FRANCE p.4

DIFFERING EUTROPHICATION GRADIENTS IN

COAST AL LAGOONS

Eutrophication conditions are described in three lagoon systems, differing in structure, catchment and connection

with the sea: the Bassin d'Arcachon on the Atlantic coast, SW France, the semi-artificial fish ponds of the Bassin d'Arcachon and the Etang du Prévost on the Mediterranean coast.

AUSTRIA p.S

PHYSIOLOGICAL ADAPTATION PROCESSES TO

CHANGES IN THE ENVIRONMENT

The properties of the phosphate uptake system of the cyanobacterium Anacystis nidulans were studied during the transition from a phosphate-deficient non-growing state to a non-deficient growing state. The paper is a detailed scientific study of the various physiological adaptation processes by which organisms react to changes in their environment.

PO LAND p.6

SUBSTITUTION OF POLYPHOSPHATES IN

POPULAR POLISH DETERGENTS

This paper describes the possible impact of certain substitutes of polyphosphates (NT A, EDT A) in detergents,

on the environment. EDT A is reported as non­biodegradable, this, coupled with a high chelating capacity may cause mobilisation of heavy metals from sediments. NT A is essentially biodegradable though there is evidence of non-biodegradable complex carry over.

UNITED KINGDOM p.7

CLEANING UP THE THAMES ESTUARY

A 69 page report "The Water Quality of the Tidal Thames", published by the Environmental Agency covers in detail the recovery of the Thames Estuary, from a heavily polluted catchment to one of the cleanest metropolitan estuaries in the

world. No phosphate restrictions were required.

j PLUS ... p.7 ,

THE PHOSPHATE FILE :

An informative booklet covering phosphate source, use and fate in the environment.

SCOPE NEWSLETIER

produced by NEWTON CONSULTING NETWORK- 9, rue Newton- 75116 PARIS FRANCE- Tel. 33-1-53-97-7698

SELECTIVE REMO V AL AND RECOVERY OF

PHOSPHATE USING A NEW CLASS OF

SORBENTS- II- PROCESS OPTIMISATION.

The main processes concerning the precipitation of

calcium phosphate in a fluidized bed were

established (see Newsletter 22). It was suggested

that an improvement in the phosphate removal

efficiency from 60% to 80% may be achieved if

process conditions are found favouring aggregation,

molecular growth, or preferably both. Thus an

optimisation of the phosphate removal efficiency

was attempted, in this second paper, by focusing on

the aggregation process.

Experiments with a fluidized bed preceded by a pre­

mixing reactor as weil as without pre-mixing were carried out.

In the first case the aggregation of the fmes with the

grains in a fluidized bed was studied. A set-up was designed to isolate the aggregation from other processes and mathernatically modeled to take into account two competing mechanisrns: orthokinetic aggregation and breakage. In the second case (i.e. normal operation of a fluidized bed) experiments with a spread type dosage were also performed. Both experiments are described in the paper. In the fluidized bed preceded by a pre-mixing reactor it was found that the aggregation model gives a fairly accurate prediction of the measured efficiency for both types of grains (fine and coarse sand) over the complete range of the total flow despite the spread in experimental data, it also showed that small grains and a low throughput favour a high aggregation efficiency.

ln the fluidized bed with the base dosage at the bottom, reactants were mixed with NaOH dosage and a high local supersaturation was obtained. Predicted efficiencies were too low suggesting processes other

than aggregation. Most of the phosphate removal occurred at the bottom of the bed. Phosphate removal efficiencies due to aggregation were equal to - 60%

and to molecular growth of- 40%.

By spreading the base dosage between at least two additional points a non-negligible supersaturation is sustained for a longer period of time, improving phosphate removal efficiency by increasing both net aggregation and molecular growth. Deviations in the model predictions were thought to be due to the contribution of the inlet stream kinetic energy to the total energy dissipation rate, suggesting that a high

energy dissipation rate is detrimental to phosphate remo val.

In conclusion, optimisation was achieved by selecting sand grains of small sizes (0.1-0.3 mm), a low superficial velocity (7xl0-3mfs) and by spreading the base addition over two locations. The highest phosphate removal efficiency was found to be 0.8 for a conversion of 0.25 after the first base dosage. The phosphate removal efficiency can be further improved by lowering the mixing intensity at the bottom of the reactor.

Wat. Res. Vo/.30. W7 pp.J589-1596, 1996. M.M.Seck/er, M.JL. Van Leeuwen, O.S.L.Bruinsma

and G.M. Van Rosmalen.

ENVIRONMENTAL IMPACTS OF NUTRIENT

REMO V AL PROCESSES

The influence of primary clarification of sewage on

nitrogen and phosphorus removal in a modified

University of Cape Town type wastewater

treatment plant (WWTP) was studied, using batch

tests, on a full scale before and after the

introduction of raw sewage. The effect on the

activated sludge population and the overall

environmental impacts were studied.

A WWTP in Holten, The Netherlands, is designed as a

modified University of Cape Town type treatment plant, operated with presettled sewage. The prirnary sludge (including precipitated phosphorus) and the secondary sludge is digested. The treatment plant consists of anaerobie, anoxie, and aerobic zones, and

primary and secondary clarifiers. Presettled wastewater

is introduced into the anaerobie zone. Retum sludge from the secondary clarifier is recirculated to the start of the anoxie zone. Mixed liquor in the anoxie zone is

2

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SCOPE NEWSLETTER

recirculated to the start of the anaerobie zone. The

WWTP is operated at a long sludge retention time

(SRT) of 45 days, and the foilowing batch tests were

carried out:

• Anaerobie phosphorus release tests

• Aerobic phosphorus uptake tests

• Anoxie phosphorus uptake tests

• Anoxie phosphorus release tests

Before the introduction of raw sewage the maximum released phosphorus was approx. 30 mg P/g volatile

suspended solids (VSS): this figure feil to 1 4 mg P/g

VSS after the introduction. The proportion of

phosphorus-removing organisms in total biomass

decreased from approx. 30-50% to 15-20%. Before

and after the introduction of the raw sewage the

contribution of denitrifying dephosphatation was

similar, approx. 40-45% of total activity - indicating

that denitrifying dephosphatation still contributed significantly to phosphorus removal after the

introduction. The phosphorus release rate was,

however, much lower under anoxie conditions than

under anaerobie conditions. The nitrification

efficiency feil from 84% to 73%, probably due to a

decrease of SRT. Less nitrate was formed in the

effluent, although the nitrogen balance indicated that

the improvement was due to extra nitrogen

assimilation because of extra sludge production. Net

energy consumption rose (+75%) mainly because of

the sludge handling but also in view of the decrease

(-45%) in methane production in the digester.

It is questionable whether the improved effluent

qua1ity imposed by governrnent regulations obtained by changing to raw sewage feeding had an overail

positive effect on the environment. This work shows

that evaluating treatment processes only on effluent

quality can lead to overail adverse effects on the

environment.

Journal of Environmental Engineering Vol. 13, N°l,

Jan. 1997 pp 33-40. MC.M. Van Loosdrecht, T.Kuba, H.M Vn Veldhuizen, F.A.Brandse, J.J.Heijnen.

THE EFFECTS OF ANIMAL W ASTE

APPLICATION TO SANDY SOILS ON DOP

LEACHING

A substantial part of total P in soil solution and Ieachates can exist as dissolved organic phosphorus (DOP), which may be more mobile than inorganic orthophosphate and so be an important P source

for surface water eutrophication. The analysis of DOP has not been included in many field studies,

nor included in models developed to predict the movement of P through the soil. This paper focuses on four experiments to investigate the effects of pig

waste application to �andy soil on DOP leaching.

• Exp. 1 examined the effect of storing pig slurry on

DOP fractionation using gel permeation chromatography.

• Exp. 2 & 3 studied immediate and long term effects

of animal waste application to soil in both laboratory

columns and outdoor maize-grown lysimeters (four

treatrnents in triplicate for 7 yr.). • Exp. 4 examined concentrations of DOP and total P

(TP) in soil solutions at various depths in a long term

field experiment, between 1971 and 1982.

The foilowing hypotheses were tested:

1 . DOP is a significant fraction of TP in leachates and

in the soil solution, and this fraction increases with

increasing soil depth.

2. DOP is a larger fraction of TP in soils heavily

supplied with slurry than soils only receiving mineral

fertilisers.

A large amount of molybdate reactive P (MRP) was

found in high molecular weight (MW) material from

pig slurry liquid. The MRP probably originated from

acid hydrolysis during the analysis. This can cause an

underestimation ofDOP content in fresh pig slurry.

In a manured sandy soil column more than 90% of P leached was present in the organic form. Results of the

field experiment showed that DOP fraction makes up the largest part of TP in soil solutions below 50cm depth. Thus the first hypothesis was found to be

correct. However the second hypothesis was rejected.

3

SUBSTITUTION OF POL YPHOSPHATES IN

POPULAR POLISH DETERGENTS -

ENVIRONMENTAL IMPLICATIONS

This paper describes the possible impact of certain

substitutes of polyphosphates (NT A, EDT A) in

popular Polish detergents on the environment.

EDT A is reported as non-biodegradable - this

coupled with a high chelating capacity may cause

mobilisation of heavy metals from sediments. NTA

is essentially biodegradable though there is evidence of non-biodegradable complex carry over.

The contribution of phosphorus from detergents to

total phosphorus load in wastewater is approx. 30-50%. Substitutes are proposed by the producers of commercial washing powders/liquid detergents: i.e.

zeolites and organic chelating ligands

ethylenediaminetetraacetic acid (EDTA) and nitrylotriamineacetic acid (NTA). Studies show that

none of them are as efficient as tripolyphosphates, nor are they neutra! for the environment.

Levels of EDTA and NTA in raw domestic sewage

were measured at each step of the treatrnent process in Hajd6w (near Lublin) in Poland inl994. The contents of EDT A and NT A in popular washing powders and liquid washing-up detergents (both Polish and

imported) were verified. Hajd6w is a mechanical­

biological treatrnent plant, with no chemical stage, typical of municipal sewage treatrnent plants in Poland. lt caters for the Lublin (400 000 inhabitants)

and Swidnik (20 000 inhabitants) communities.

Studies show that no polyphosphates are found in the raw sewage th us only data for EDTA and NT A was presented. NT A was not found in the raw sewage

although the most common powder and the least common (due to its high priee) concentrate powder contain large amounts of NT A. Waste from industry

may dilute the stream at the entrance to the plant so

NT A was not detected. Results for EDTA were very different : almost ali washing-up liquids contained

EDTA, except a liquid produced in Western Europe,

advertised as "environmentally friendly". Results for

powders varied, the concentrate powder contained

highest levels of phosphates and chelates and was the only product containing EDTA and NTA. The powder

advertised as "phosphate free" contained 2.55g/kg of phosphates in the orthophosphate form and high levels

of EDTA. EDTA was found in the raw sewage - the level did not decrease as it passed through the

treatrnent plant.

EDTA is a strong complexing agent for divalent and polyvalent metals. In Poland, industrial wastewater is often rnixed with municipal wastewater after primary pre-treatrnent. Naturally heavy metals forming strong

complexes with EDTA ligands are found at low concentrations. Higher concentrations of Ca and Mg may occur but Ca-EDTA and Mg-EDTA have stability constants a few orders of magnitude lower.

The paper concludes that "phosphate free" (i.e. free from polyphosphate but not from inorganic phosphorus) detergents are not neutral for the environment. Stable chelating ligands may cause

mobilisation of heavy metals from sediments. To

prevent unexpected effects in the water environment, limitations of non-degradable chelates is necessary.

The EDTA/NTA complex interaction with heavy metals in soil and water environments merits further careful study. Chemistry for the Protection of the Environment 2

edited by Pawlowski et al, Plenum Press, New York, /996. M.R.Dudzinska & A.Montusiewicz.

CLEANING UP THE THAMES ESTUARY

A 69 page report entitled "The Water Quality of

the Tidal Thames" bas been published by the

Environment Agency. It covers in detail the

recovery of the Thames Estuary, from a heavily

polluted catchment to one of the cleanest metropolitan estuaries in the world. No phosphate

restrictions were required to manage the 14 000

km2 area with 12 million population.

The recovery was achieved by the restoration of water quality. The most important factor in water quality

control in the Thames is dissolved oxygen and

improved sewage treatrnent standards, particularly

under summer conditions in order to ensure adequate

oxygen reserves i.e. 30% saturation ..

6

SCOPE NEWSLETTER

Eutrophication was not considered to be a problem in

the main body of the estuary due to strong tidal flows,

salinity variations and high turbidity, precluding the

development of significant algal blooms, although algal blooms have occurred in sorne enclosed waters, e.g. London Docks. Phytoplankton were considered to

be important in their capacity to convert inorganic

material to organic matter, oxygenate water through photosynthesis and deoxygenate through respiration and decomposition. This remarkable recovery has supported over 115 species of fish and nearly 300 000

seasonal water birds.

The challenge now is to ensure that this achievement is maintained and built upon. As the Thames Estuary Environment Management Plan recognises "nowhere in the country are environmental pressures and

competing demands for space and resources greater than on Thameside". To achieve "an Estuary which is

valued as a place to live, work and relax: an environmental asset and a focus for economie growth" it is vital that resources are managed in a sustainable way. "The Water Quality of the Tidal Thames",

Environment Agency Report 1997, ISBN 011 31025 2.

THE PHOSPHATE FILE :AN INFORMATIVE

BOOKLET COVERING PHOSPHATE SOURCE,

USE AND FATE IN THE ENVIRONMENT

The Centre Européen d'Etudes des Polyphosphates (CEEP), a CEFIC sector group representing the European Phosphate producers, have recently

published a 14 page booklet entitled «Phosphate­File».

Both clear and concise, this booklet was prepared as an

informative study of phosphate and the environment. From its geographical extraction sites, its nutritional

impact, its uses in agriculture through to an in-depth

study of phosphate in the environment, the « Phosphate File » covers ali aspects related to this

valuable resource. Moreover with global development, the need for phosphorus is expected to increase in agriculture and industry thereby placing constraints on this valuable finite resource.

Analysing the interactions between phosphates and

water quality, the « Phosphate-File » lays out the need for improved sewage recovery as a means not only to

retain phosphorus but to recover and reuse both directly as a rich fertiliser or, utilising new extraction

techniques, retum it as a raw material for detergent and other product applications. Clearly this element which is not replaceable and essentially rare lends itself ideally to the principle of sustainable development. Thus, what is already considered the most effective builders in detergents would also become the most

environmentally adaptable. « Phosphate File » 14p. 1997, order direct/y from SCOPE Newsletter or CEEP, Avenue Van

Nieuwenhuyse 4. Bte 2-b- 1160 Brussels, Belgium.

7

The SCOPE Newsletter is produced by the CENTRE EUROPEEN D'ETUDES DES POL YPHOSPHA TES, the phosphate industry's research foundation and a sector group of CEFIC (the European Chemical lndustry Council).

The SCOPE Newsletter seeks to promote a better understanding of the sustainable use of phosphate and the role of phosphate in the environment.

The SCOPE Newsletter is open to input from its readers and we welcome ali comments or information. Contributions from readers are invited on ali subjects conceming phosphates, detergents, sewage treatment and the environment. Y ou are invited to submit scientific papers for resume or full publication, to send comments on the studies mentioned in this Newsletter or other scientific or technical views.

For more information, please contact : Newton Consulting Network- who produce this SCOPE Newsletter-

9, rue Newton, Paris, France, Te133-1-53-57-7698 Fax 33-53-57-7679 e-mail : newton@net.asi.fr

The SCOPE NEWSLETTER is also available on INTERNET at : http://www.asi.fr/scope

lfyou want the SCOPE NEWSLETIER to be distributed to other contacts

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ON PHOSPHATES

SCOPE NEWSLETTER IN EUROPE

NUMBER TWENTY TWO

ü.S.A p.l

SELECTIVE REMOV AL AND RECOVERY OF PHOSPHATE USING A NEW .CLASS OF SORBENTS

A new class of sorbents - polymerie ligand exchangers (PLE) - have been tested in a ftxed bed column allowing the selective removals of phosphate through ligand type interaction. The sorbent is also amenable to efficient regeneration and phosphate can be recovered as magnesium ammonium phosphate (struvite), a high value fertiliser.

'l'BE NE'l'BERLANDS p.l

CALCIUM PHOSPHATE PRECIPITATION IN A HXIDIZED BED : A BLACK BOX APPROACH.

This paper studies the precipitation features of calcium phosphate in a fluidised bed reactor in a concentration range between 5 and 10 mg P/1 and establishes the conditions for optimum phosphate removal efficiency. A method is presented to select process conditions where co-precipitation of unwanted phases is avoided.

üNI'I'ED KINGDOM p.3

MONITORING OF SOIL DERIVED

PHOSPHORUS IN SURFACE RUNOFF

This paper examines the rates of P transfer from soil to waters from intensively managed grazed grassland by surface runoff plus interflow to 30 cm depth, in a poorly drained soil, in relation to rainfall inputs during 12 months. lt concludes that grasslands are a significant source of diffuse P inputs to surface and esturine waters and may cause eutrophication.

'l'HE NE'I'BERLANDS p.4

PHOSPHATE & NITROGEN INFLUENCE FISH STOCKS

This report is an inventory of current knowledge, carried out at the request of the Du teh Commodity Board for Fish, in response to the debate on the connection between depleted stocks of flatfish and the considerable reduction in the quantity of phosphate in coastal waters.

PACIF1C OCEAN p.4

DRAMATIC CHANGES IN SURFACE WATERS DUE TO IRON ENRICHMENT EXPERIMENT

JULY 1997

An in-situ iron fertiliser experiment was carried out twice, (1993 and 1995), in the eastern Pacifie Ocean to observe the effect on phytoplankton abundance.

AUSTRALIA

FOOD WEB INTERACTIONS AND BIOMANIPULATION

p.5

The control of phytoplankton biomass in severa! Australian reservoirs was studied. Food web interaction of Australian biota were explored at different levels. In order to manipulate fish communities to reduce phytoplankton . biomass a thorough understanding of the process in the plankton­associated food web is needed.

üNI'l'ED KINGDOM p.6

ENVIRONMENTAL FACTORS AND NUTRIENT REGULATION IN NATURAL WATERS

This review seeks to identify the key areas in aquatic science required for future management of algal problems in freshwaters.

SWI'l'ZERLAND p.7

SUCCESSFUL WATER PROTECTION MANAGEMENT

Lake Zurich, Lake Walenstadt and the Zurichobersee make up a connected system of lakes with differing population densities, geographical and meteorological conditions making them suitable for studying the effectiveness of water protection measures.

PLUS ... p.8

RECENTL Y PUBLISHED REPORT "PHOSPHORUS REMOVAL AND RECOVERY TECHNOLOGIES"

NORDIC ECO-LABELLING SCHEME OPEN FOR PHOSPHATE BASED DISHWASHING DETERGENTS

IAWQ VIDEO ''NATURE'S WAY" BEST MANAGEMENT PRACTICES (BMPs) THE CONTROL OF WATER DIFFUSION

NEW WEBSITE FOR ENVIRONMENTAL INFORMATION

SCOPE is a non-commercial, non-profit making European association based in Brussels. Ils a1m 1s to provide a platform for objective and scientific informat1on on the effects of phosphate-containing and phosphate·free detergents on the enwonment.

SCOPE NE\\SLETTER produced by European Communications Unit - 20, rue de l'Arcade - 75008 PARIS - FRANCE - Tel. + 33 1 44 94 80 70

SCOPE : Scientific Committee on Phosphates in Europe ·Association Sans But Lucratif sise à Bruxelles et soumise à la Loi du 27 juin 1921

SELECTIVE REMO V AL AND RECOVERY OF PHOSPHATE USING A NEW CLASS OF

SORBENTS

The presence of various competing anions make the selective removal of low concentrations of phosphate after secondary treatment particularly difficult. In this research a new class of sorbents -polymerie ligand exchangers (PLE) - have been tested in a fixed bed column allowing the selective removal of phosphate through ligand type interaction. The sorbent is also amenable to efficient regeneration and phosphate cao be recovered as magnesium ammonium phosphate (struvite), a high value slow-release fertiliser.

Phosphorus cao be removed through either chemical precipitation or biological nutrient removal (BNR), and transferred to the sludge phase.

4 successive column runs were carried out in the laboratory using treated wastewater from the Bethlehem Sewage Treatment Plant in Pennsylvania, U.S.A. The objective was to validate: * PLE's high affinity with phosphate compared to sulphate * extended colurnn runs with complete phosphate removal with synthesised wastewater and secondary effluent * regeneration of the exhausted colurnn for phosphate recovery.

A specially chelating polymer containing only nitrogen donor atoms (DOW N2) was used as PLE after loading with copper (11) and 2 other commercially available resins - IRA-958 (a strong base anion exchanger) and IRC-718 (a copper loaded chelating exchanger). were used for comparison. The resins were conditioned following the standard procedure of cyclic exhaustion, and the following chemical analyses were carried out: sulphide, chloride, phosphate, bicarbonate, copper and TOC analyses.

The breakthrough histories were measured and the influent compositions, pH and operating hydrodynamic conditions - empty bed contact time (EBCT) and superficial liquid velocity (SL V) were identical for each of the 3 sorbents. The phosphate breakthrough for DOW 2N-Cu occurred much later than for the other sorbents, in spite of high concentrations of competing bicarbonate, sulphide and chloride. DOW 2N-Cu also offered much higher phosphate uptake capacity than IRA-958. Total anion exchange capacity was found to be equal to the copper (Il) loading capacity of DOW 2N, suggesting that fixed copper (11) anions in the polymer provide the primary sorption site for anions.

Following exhaustion of PLE after phosphate breakthrough more than 90% phosphate was recovered in less than 10 bed volumes - both electroselectivity reversai at high ionie strength and lower affinity of

H2P04- compared to HP042- provide the reasons for efficient phosphate regeneration.

Phosphate is an anionic ligand and its sorption onto DOW 2N-Cu involves electrostatic interaction due to fixed positive charges in the polymer phase and accompanying lewis acid-base interaction with immobilised copper ions.

lt bas been demonstrated that a new fixed-bed sorption process is capable not only of removing phosphate selectively from municipal and industrial wastewater but is also amenable to efficient regeneration leading to phosphate recovery. With the current concem over nutrient removal from wastewater and water reuse, the process is expected to be an economically viable one in the near future. Water Science Tech. Vol. 33 1996 Department of Civil and Environmental Engineering 13E Packer Avenue, Lehigh University, Bethlehem, PA 18015, US.A. Dongye Zhao and Arup K. Sengupta.

CALCIUM PHOSPHATE PRECIPITATION IN A FLUIDIZED BED : A BLACK BOX APPROACH

Emphasis in recent years bas been focused on improving processes which lead to enhanced phosphate recovery - this paper studies the precipitation features of calcium phosphate in a fluidised bed reactor in a concentration range between 5 and 10 mg Pli and establishes the conditions for optimum phosphate removal efficiency. The feasibility of a process based on the precipitation of magnesium phosphate was shown for waters with a low calcium content. A method is presented to select process conditions where co­precipitation of unwanted phases is avoided.

Currently severa} processes for phosphate removal based on the precipitation of phosphate salts are used -conventionally a reagent is added to precipitate phosphorus salt, which becomes incorporated in the sludge by-product.

A screening study of a fluidised bed process with high inlet phosphate concentrations was carried out, by varying conditions such as the inlet concentrations of calcium and phosphate and the outlet. Phosphate removal efficiency, mechanical stability of the phosphate grains and the effects of carbon and magnesium ions (which can interfere in the process) were determined.

The process is based on a precipitation of calcium phosphate obtained by mixing a phosphate solution with calcium ions and a base. The fluidised bed

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reactors (of 2 different sizes, which did not appear to affect the pro cess) were filled with sand grains and then fed continuously with aqueous solutions containing phosphate ions, calcium ions and a base. Phosphate covered grains were removed from the bottom of the bed and replaced regularly with fresh sand grains. At the same time two unwanted processes occurred leaving small particles ("fmes"): primary nucleation in the liquid phase and abrasion of the mineral layer in the bed. The fmes leave the bed with the rernaining phosphate not recovered in the reactor. However aggregation with the fmes and the grains can contribute to phosphate recovery. The concentrations of P, Ca, Mg and Na were measured - total carbonate concentration was measured by acid-base filtration, fme and grains by X-ray diffraction, the grains were also analysed by optical rnicroscopy and scanning electron rnicroscopy (SEM). The grains and fmes produced appeared to be amorphous calcium phosphate (ACP) except for one experiment at the highest P concentration where DCPD ( dicalcium phosphate dihydrate ) was formed.

Optimum conversion is the one corresponding to maximum efficiency - if water does not contain magnesium or carbonate ions the supply of the base should promote conversion of 50-60% of the incoming phosphate: the presence of these ions increased these values to 80-95% - most wastewaters are in this latter category. Low conversion values are desirable as they imply low base consurnption (an important element when considering operating costs). The amount of base needed to obtain the required conversion can be calculated if the composition of the water to be treated is known. Corresponding outlet pH values were 7.5-9.

lt was concluded that phosphate removal efficiency in a fluidised bed reactor depends on composition of the water treated : a maximum efficiency of 50% was achieved. This corresponded with a low phosphate input. Wat.Res. Vo/.30, N°7, pp 1677-1685 Laboratory for Process Equipment, Delft University of Technology, Leeghwaterstraat 44, 2628 CA, Delft, The Netherlands & !PA P.O.Box 7141, Cidade Universitt:iria, 01064-970, Siio Paulo S.P. Brazil. M.M.Seckler, O.S.L. Bruinsma & G.M. Van Rosmalen, January 1996.

MONITORING OF SOIL DERIVED PHOSPHORUS IN SURFACE RUNOFF

This paper examines the rates of P transfer from soil to waters from intensively managed grazed grassland via surface runoff plus intertlow to 30 cm depth, in a poorly drained soil, in relation to rainfall inputs during 12 montbs. In order to gain an understanding of the mecbanisms involved total pbosphorus (TP) and molybdate reactive pbosphorus (MRP) are considered witb temporal differences in runoff discharge. It concludes tbat

grasslands are a significant source of diffuse P inputs to surface and esturine waters and may contribute to eutropbication.

Seven 1 ha grazed lysimeter plots managed for the past 12 years as intensive grassland at North Wyke, Devon were monitored. The existing sward is dorninated by Loliurn perenne L and other grass species. The soil is a clayey non-calcareous pelostagnogley of the Hallsworth Series. Before analysis water was collected from each plot lysimeter and channelled through a continuons level recording reservoir and then through V -notch weirs. The plots were managed for N studies, but this involved inputs of triple super phosphate (TSP) fertiliser. An observationallempirical approach was used, involving both routine and storm monitoring. Modelling the data was difficult as they were skewed by the occurrence of low frequency, high intensity events.

Higher discharge was associated with higher TP concentration although this was not the case for MRP, implying that unreactive P and particulates > 0.45 J.Lm in size play a major role in the export of TP. Thus mechanisrns such as hydrolysis and mineralisation of organic P and erosion of particulate P may be important processes for releasing P from these soils. Patterns of TP concentration and loading and suspended sediment throughout the period of hydrograph were more complex. The delayed peak in TP concentration was associated with the second peak in the suspended sediment , suggesting that sediment transfer rather than water movement, as such, was important. More research is needed to understand the dynarnics of P runoff, particularly when it is transferred from the soil surface into surface drainage systems.

Release of high concentrations of TP and MRP

( exceeding 1000 !lg 1-1) are thought to relate to pasture conditions at that time. lt was suggested that 3 factors were responsible:-

* short term management history - excreta are a direct source of P and have long term effects on the EPC in soils, but the design of the drainage/sampling system did not reflect localised nutrient concentration from excreta. Introduction of cattle may also have resulted in "poaching" - both dung deposits and poaching were prevalent around drink troughs and gateways in the plot lysimeters - slurry application and grazing during periods when the soil was close to saturation lead to much higher !osses of P than during dry periods. The release of P may have been exacerbated by the wetting and drying cycle. * rainfall intensity - high intensity rainfall may have caused erosion of particulate P and contributed to high losses of TP compared to MRP. * estimated P loads in grassland soil - a total annual

loss of c. 3kg of TP ha - 1 was estimated.

3

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Minimal loss strategies have previously been suggested. If P is added as basic slag rather than TSP a slow release of P would occur when it was ploughed and incorporated into the soil matrix. Direct injection methods of slurry and sludge additions have been suggested to minimise !osses, the use of buffer zones has also been discussed. Most loss strategies have focused on arable systems and more research is required to assess the importance of managing grassland. However in sensitive catchments it is advisable to avoid spreading fertiliser and manure at times when runoff is likely to occur. Impacts of re­seeding pasture, grazing and pasture differences may also be important management considerations affecting P loss and are important areas for future research. P.M. Haygarth & S.C. Jarvis, ref Wat.Res. Vol. 31, W 1 pp 140-148, 1997.

PHOSPHATE AND NITROGEN INFLUENCE FISHSTOCKS

This report is an inventory of current knowledge, carried out at the request of the Dutch Commodity Board for Fish, in response to the debate on the connection between depleted stocks of flatfish and the considerable reduction in the quantity of phosphate in coastal waters.

From 1950-80 amounts of phosphate and nitrogen in these coastal waters rose considerably, and when levels then fell phosphate suffered a greater decrease than nitrogen, leading to an excess in nitrogen.

It is probable that plant growth increased with the increase in nutrients, leading to a larger number of Seabed organisms ( copepods and decapods) which are an important source of nutrition for fish. There appears to be a connection between the increase in nutrients and the survival and increased growth rate of the larvae of plaice and sole - with important positive consequences for fish catches.

The decrease in phosphate has lead to disequilibrium over the past 15 years - the nitrogen excess has caused an increase in marine phosphorescence, undesirable toxic species of algae (unsuitable for consumption) and thus negative effects on the food chain;

Restoration of the equilibrium is desirable for both water and fish management, although no decrease in nitrogen levels can be expected in the near future and restoration at the current level is undesirable (leading to an excess of algae ). The only remaining option is to allow the concentration of phosphate to increase. A policy involving a reduction of nitrogen discharges and an increase in phosphate discharges would thus be the most appropriate and would benefit the fishing sector. Marine Biology Research Group, University of Groningen, W.J. Wolff, Dr H.J. Nanninga & Dr R. Boddeke 1997.

DRAMATIC BIOLOGICAL AND BIOCHEMICAL CHANGES IN SURFACE WATERS DUE TO IRON ENRICHMENT

EXPERIMENT

An in-situ iron fertiliser experiment bas been carried out twice , in 1993 and 1995, in the eastern Pacifie Ocean in order to observe the effect on phytoplankton abondance. Despite high concentrations of the major nutrients, nitrate and phosphate, phytoplankton abondance remains low in this area. These features characterise the 3 "high nitrate, low chlorophyll" (HNLC) regions -including the eastern equatorial Pacifie, the ice-free Southern Ocean and the Sub Arctic North Pacifie Ocean.

Papers report that it is the extraordinarily low availability of iron which limits phytoplankton growth in these HNCL areas: although iron is almost insoluble in sea water, it is an essential trace nutrient required by phytoplankton for many biochemical processes - e.g .. chlorophyll synthesis and biochemical processes.

Iron Exl, carried out in 1993, reported that a single dose of iron raising the dissolved iron concentration to

4nm, over 64km2 resulted in significant increased phytoplankton abundance and production rate, but had limited effect on nitrate concentration or partial pressure of C02. Unfortunately the experiment ended abruptly when the fertilised patch sank beneath a layer of less dense water. Although the experiment verified the iron hypothesis, the issue of whether iron fertilisation could relieve the HNCL condition was left unresolved.

In Iron Exil, carried out in 1995, the same amount of dissolved iron was added from a ship into the surface �·---­

layer of a square patch of ocean in the eastern equatorial Pacifie, in three sequential infusions over a week, to sustain the increase of dissolved iron in the

surface layer over 72km2. The fertilised patch, tagged with a drogued buoy and a biologically inert tracer (SF6), whilst drifting 1500 km. Untreated water outside the patch served a control.

The effect of the fertilisation was immediate and dramatic - phytoplankton photosynthetic capacity growth rate and abundance increased, whilst nitrate concentration declined by half. As the phytoplankton bloomed its species composition changed radically -diatoms became dominant and accounted for most of the increased use of nitrate As the bloom developed the partial pressure of co2 in the middle of the patch

decreased rapidly, reducing the ocean-to-atmosphere C02 flux by 60%. There was also an increase of

dimethyl sulphide (DMS) in the bloom which may have a role in global warming.

4

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SCIENTIFIC COMMITIEE

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However, the stimulated production was short lived -within a week of the fmal infusion, indicators of the last phytoplankton physiological condition returned to the sarne levels as before, phytoplankton bloom waned (presumably due to grazing and sinking) - and contrary to expectations the was no indication that the iron was retained and efficiently recycled within the biota of the surface layer. The consequences of larger scale, longer term inputs of iron are uncertain.'

Iron Exil reinforced the notion that availability of iron lirnits cell division rates, abundance and production rate in phytoplankton. Although zooplankton increased in abundance and grazing rate, the response was insufficient to prevent the diatom bloom. lt also showed that, along with grazing, iron limitation determines the composition of natural assemblages of phytoplankton. hon fertilisation did little to disrupt the natural grazing balance of the small species. The larger-sized phytoplankton are probably under the most stress in HNCL regions, and division rates should be low, although evidence is contradictory. Nature Vo/.383 JO October 1996 p.475 Bruce W Frost.

FOOD WEB INTERACTIONS AND BIOMANIPULATION

The control of phytoplankton biomass in several Australian reservoirs was studied. Food web interaction of Australian biota were explored at different levels: laboratory trials, in mesocosms, by analysing the time series of plankton and fish biomass in reservoirs. In order to manipulate fish communities to reduce phytoplankton biomass a thorough understanding of the process in the plankton-associated food web is needed. The aim of biomanipulation is the establishment and maintenance of a ratio of planktivores/piscivores sufficient for water quality requirements.

In Lake Hume (surface area 202.5km2, 41m depth)

and Lake Dartmouth (63km2, 170m depth) Daphnia biomass accounted for more than 50% of the observed variance in total phytoplankton biovolume (TPB) in spring/summer '94/95. When zooplankton biomass and nutrients were manipulated in water from the lakes, total chlorophyll-a was significantly affected by grazers in 8 out of 12 experiments and by added nutrients in 9 out of 12 experiments - the relative importance of the 2 effects changed seasonally. Acoustic biomass of pelagie fish (echo integration above 90dB) also varied seasonally - peaking in autumn and having minima in spring. Acoustic fish biomass was highest in eutrophie (Queensland) lakes and lowest in oligotrophic (Snowy Mountains) lakes.

In contrast to other continents, Australian reservoirs contain established populations of fish in the pelagie zone. It bas been demonstrated that a strong negative

correlation between mean crustacea body length and TPB exists, although maximum mean length is much higher (more than 2mm) than elsewhere, suggesting that the potential for biomanipulation will be higher. This larger mean value is due to the presence of the zooplankter Daphnia Carinata, a species widespread in Australia.

The planktivorous fish of Australian reservoirs are relatively small and they may deplete small zooplankters, resulting in the promotion of this Daphnia.

In Lake Dartmouth small flat headed gudgen, Philypnoden grandiceps, were co-existing with Daphnia Carinata in the pelagie zone, and a positive correlation between crustacean body length and fish acoustic biomass was found. Such interactions suggest that biomanipulation may involve creating conditions to protect sorne planktivorous fish. lt was also suggested that sorne planktivores stirnulate algal growth by excreting nutrients.

Final control will depend on which force prevails: zooplankton grazing or nutrient supply from fish and other sources. Such complex interactions show the necessity of analysing a lakes' food web before applying biomanipulation as a management option -further development of the food web theory under Australian conditions is needed. CRCFE Murray­Darling Research Centre, P.O.Box 921, A/bury 2640, Australia. Dr V.F. Matveev & L.K. Mateeva 1996.

ENVIRONMENTAL FACTORS AND NUTRIENT REGULATION IN NATURAL WATERS

This review seeks to identify the key areas in aquatic science required for future management of algal problems in freshwater. The short ter rn

management of problems related to toxic cyanobacterial blooms in the U .K. bas been met by raising the general public's awareness, defining the role of public bodies in the matter and introducing monitoring programmes.

Agricultural fertilisers play a major role in eutrophication - the change in English lakes in the 1950's was abrupt and coincided with the increased usage of fertilisers for grass production, a population increase, an increase in the influx of tourists, the introduction of piped water, sewerage and secondary wastewater treatment - it is impossible to separate these effects. The diffuse and point source of inputs of nutrients from agricultural practices are still ill defined and the effects of nutrient regulation difficult to predict.

The author deduces that if the export of nitrogen and, particularly phosphorus is increased there is sorne pro rata increase in the capacity of water to support

5

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primary production. Production is also subject to other constraints, e.g. the availability of light and temperature - different phytoplankton species differentiated selectively by the interplay of these factors. Although the development of blooms have been associated with eutrophication and phosphorus concentration, it is not apparent that cyanobacterial biomass requires any mass specifie contribution of phosphorus.

It is imperative to understand that it is a question of dynamics - bloom forming cyanobacteria are one of the slowest and most light sensitive phytoplankton species. This is the main link between cyanobacterial blooms and eutrophication: the avoidance of cyanobacterial production is not a question of eliminating all phosphorus inputs, but ensuring optimal physical and chemical conditions.

There is a wide range of different forms of phosphorus which differ in their availability for uptake by algae. the main agricultural export is in particulate form -clay, fme sand and detritus. Its role in eutrophication is considered to be subordinate to secondary sewage treatment - demonstrated by the rapid improvement in the condition of lakes benefiting from tertiary wastewater treatment.

As most biological material produced is destined for the permanent sediment, it must be considered how often components can be reused in biomass formulation before being buried. Much of the flux of phosphorus is held in iron (III) hydroxide and reuse depends on reduction of the metal to the iron (II) form.

The released phosphorus is biologically available to the organisms in contact with it, thus the significance given to solution events is understandable. However, it is unclear how well this phosphorus is used, as it generally remains isolated from production sites in surface waters. Deep lakes do not tend to recycle phosphorus, whilst shallow lakes do so almost continuously - in shallow lakes containing macrophytes, the macrophytes take up and accumulate nutrients from the water and sediment.

A combination of various factors acting serially drives the seasonal changes in mass and species composition in the planktonic community, offering a choice of solutions to combat eutrophication. The extent of the influence of any one mechanism must be considered when selecting a control method. Techniques may be categorised accordingly: * Nutrient removal - the most important point sources of phosphorus are those from wastewater treatment plants, thus control of phosphorus loading is achieved by precipitation of phosphorus with iron salts or by biological removal. * Catchment management - This is a longer term approach although methods to reduce diffuse sources of nitrogen have already been adapted for the

protection of drinking water rather than eutrophication - methods include crop zonation and reduced fertiliser application. These techniques are developing rapidly but their nutrient removal efficiency bas yet to be quantified. Entry of nutrients to lakes can also be reduced using pre-lake techniques, including the installation of treatment plants to remove phosphorus. Most eutrophied lakes have large amounts of phosphorus isolated in their sediments as iron salts or calcite - this is a particularly effective solution in smaller, shallower lakes. * Physical controls - these are really only applicable in lakes, since the effects of river morphology on eutrophication is not well enough understood - the most commonly used method for long term eutrophication control is artificial destratification, which aims at breaking down lake stratification in __

summer months. W ork in the Lund Tubes in Blelham Tarn suggests that intermittent destratification enhances this method by creating instability in the algo-community resulting in no dominant species.

Although this method is attractive in cost terms there is controversy over its efficacy and few lakes in the U .K. are deep enough for it to be used. * Bioremediation - recently much work on the understanding of biological process in lakes has been done, leading to the development of "ecotechnical methods", manipulating the trophic status; Biomanipulation is essential in the restoration of shallow lakes with high rates of phosphorus sediment recycling.

However, since concentrations of available phosphorus required to control primary production are very low

(5-10 J.lg 1-1 total dissolved phosphorus) the reduction of nutrients from any one source will be ineffective. -�

The National Rivers Authority bas developed a

framework for gathering and presenting scientific evidence including the publication of "Action Plans"--� on a case by case basis. This should then be subjected to a cost-benefit analysis to achieve agreement of all those involved before the plan is implemented. Excerpt

from the RC Publication "Agricultural Chemicals and the Environment" 1996 ISBN 0-85404-220-2 pp27-4J.A.J.D. Ferguson, M.J Pearson & C.S. Reynolds.

SUCCESSFUL WATER PROTECTION MANAGEMENT

Lake Zurich, Lake Walenstadt and the Zurichobersee constitute a connected system of lakes with differing population densities, geographical and meteorological conditions thereby making them suitable for studying the effectiveness of water protection measures.

Although there is little research on the lakes before 1950, it is known that the eutrophication of Lake -­

Zurich began around 1890. Stepwise wastewate1

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treatment, with both mechanical and biological stages, was introduced in the 1950's and 1960's, which greatly reduced amounts of DOC, TOC and BOD. In the 1970's phosphate precipitation by chemical means was introduced, leading to a lower phosphorus input, reflecting a decrease in phosphorus concentration. However a significant reduction in algal biomass is only observed when phosphorus concentration sinks

below 5 Jlg 1-l, and even then a delayed reaction of the phytoplankton biomass over severa! years must be expected (as in the case of Lake Walenstadt). Between

5 - 60 Jlg I- 1 no sporadic mass development occurs, but neither is there any marked reduction of the average algal biomass of 1 to 2 mg/1. When

phosphorus concentration is above 60 Jlg I- 1 short periods of moderate mass development can occur , although they have little negative effect on the lake (as in the case of Lake Zurich). Currently there is no information on the biomass development at higher phosphorus concentrations, since the influx of phosphorus into the lake is limited by protection measures resulting in a maximum concentration of 1 30

Jlg 1-1 .

Between 5-60 J.Lg 1-1 phosphorus, changes in phytoplankton composition are observed e.g. as phosphate levels feil blue-green algae, particular1y the genus Oscillatoria, reappeared in Lake Zurich. The biomass of zooplankton is dependent on the supply of phytoplankton, as a consequence the decrease of certain algal groups of phytoplankton was followed by a decrease in zooplankton.

The ban on phosphates in detergents (198 6) has had no additional effect on the phosphate content of the lakes investigated. The residual concentration of phosphate in the outflow from wastewater treatment plants is largely independent of phosphate concentration in untreated wastewater.

As far as drinking water processing from lake water is concemed further reduction of phosphate is unnecessary. The effect of phosphate fluctuations

between 5-60 Jlg 1-1 on biomass is srnall, thus replacing phosphate in detergents with other chemicals is questionable, particularly as their effects and degradation in lakes and drinking water are not yet known. The flocculation filtration stage now in place in the waste-water treatment process has been found to be effective in removing bath phosphate and organic substances from wastewater.

The costs relative to waste-water pollution and eutrophication problems are enormous and include waste-water treatment, lake water protection and continuing drinking water processing. Capital costs are a continuing burden to water supply authorities - the depreciation period for the plants is 40 years. Users in

Zurich pay 3.06 SFr/m3 for bath drinking water and wastewater treatment.

Overall water protection measures in the area are effective, leading to better quality lake water, which in tum is processing to excellent drinking water.l996 Water Supply, Vo/.14, N°s 314, 415-437. Zurich Water Supply Authority, Quality Control, Hardhof 9 P. O. Box, CH Zurich, Switzer/and. H.P. Klein & U. Zimmermann.

RECENTLY PUBLISHED REPORT­

"PHOSPHORUS REMOV AL AND RECOVERY

TECHNOLOGIES"

The Imperial College of Science and Medicine bas carried out a world-wide review of the scientific and technical possibilities for the recovery and recycling of phosphorus in sewage. The report was sponsored by the phosphate industry's research foundation, with the aim of stimulating discussion and subsequent research­development into the recovery of this essential resource. SCOPE subscribees will be receiving a copy of this report. If you wish to obtain a five page synopsis please contact E.C.U who publish this newsletter for SCOPE (see back caver for details). S. Brett, G.K. Morse & J.N. Lester. Environmental and Water Resource Engineering Section, Imperial Co/lege of Science, Technology and Medicine, 1997. ISBN 0 9484ll JO 0

THE NORDIC ECOLABELLING SCHEME

OPEN FOR PHOSPHATE BASED

DISHW ASHING DETERGENTS

Since 1989 a voluntary, positive ecolabelling scheme bas been operating in Finland, Norway, Sweden and Iceland with the aim of informing consumers in the selection of products which are !east harmful to the environment. The criteria for the ecolabel, the Swan, are based on a product's environmental impact throughout its lifecycle. A recent criteria document covering dishwasher detergents has been published by the Nordic Ecolabelling board. The document states that "phosphate and other phosphorus compounds may be included ". - and the Swedish lnstitute of Standards (SIS) has decided that products containing up to 53% STPP are eligible for the Swan label. This decision of the Nordic Ecolabelling Board recognises STTP as an environmentally acceptable builder for detergents.

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IAWQVIDEO "NATURE'S WAY"

BEST MANAGEMENT PRACTICES (BMPs)

THE CONTROL OF WATER DIFFUSION

This new video has been produced to introduce a range of Best Management Practices (BMPs) and sti.mulate interest in these control approaches to diffuse pollution. The video illustrates the principles developed from research, working into practice and seeks to encourage techniques of source control and treatment train approaches. The video is designed for a wide audience including water agencies, land users, developers, urban/agricultural engineers, regulators ... Particular attention is given to :

- grass swales and buffer zones/strips - infiltration systems - wet ponds - stormwater wetlands

1bis 26 min. video is available for a processing charge of f9.50 from: International Association of Water Quality (lA WQ) Duchess House, 20 Mason's Yard Duke Street St James's London, SWlY 6BU EN GLAND

NEW WEBSITE FOR ENVIRONl\tiENTAL

INFORL'\1ATION

Drs. G. Fred Lee and Anne Jones Lee who have been active for many years in the field of eutrophication­related water quality have now begun to publish their papers and reports on their web site http://members.aol.cpomlgfredlee/gfl.htm. Further information on the site and the publications can be obtained from Dr. G. Fred Lee at gfredlll@aol.com.

The SCOPE Newsletter is produced by the SCIENTIFIC COMMITTEE ON PHOSPHATES IN E UROPE, a non commercial, non profit-makin association (Association Sans But Lucratif) based in Brussels. The association includes international groups headquartered in Belgium, France, Spain, Sweden and the UK, producers of a wide variety o detergent ingredients including phosphates. Its aim is to provide a platform for objective and scientific information on the effects of phosphate containing and phosphate-free detergents on the environment. The SCOPE Newsletter is open to input from its readers across Europe and we welcorne ail comments or information. Contributions from reader are irivited on ail subjects concerning phosphates, detergents, sewage treatment and the environrnent. Y ou are invited to submit scientific pape for summary to send comments on the studies mentioned in this Newsletter or other scientific or technical news.

For more information, please contact : E.C.U. (European Communications Unit) •

who produce this Newsletter 20, rue de l'Arcade, 75008 Paris, France, Tel.+ 33 1 44 94 80 70 Fax +33 1 44 94 81 01 E-mail ecu@net.asi.fr

The SCOPE NEWSLETTER is a1so available on INTERNET at: http://www.asi.fr/scope

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1�-·--------------------------�SC�I�EN�T�IF�IC�----- --------------------­COMMITIEE

ON PHOSPHATES

SCOPE NEWSLETTER IN EUROPE

NUMBER TWENTY

UNITED KINGDOM p.2

PHOSPHORUS LEACHING INVESTIGATED IN THE BROADBALK EXPERIMENT

Movement of P vertically through and out of soil is generally considered to be of little importance, unless soils become P saturated (following heavy manure applications), due to high P fixation capacity of soils. F actors controlling these losses are generally considered to be related to soil type, pH and weather rather than fertiliser use. These findings have been questioned by data from the Broadbalk Continuous Wheat Experiment at Rothampsted.

UNITED KINGDOM p.3

ACID LAKES TREATED WITH PHOSPHATE SOLUTION

Lakes acidified by airborne pollutants typically have low biological productivity and support an impoverished flora and fauna. Although they can be neutralised by adding base (lime), the resulting calcium rich water supports animal and plant communities unlike those in natural softwater lakes. This paper examines the results of a 3 year experiment, a pretreatment year, followed by 2 years of fertilisation, in the Lake District.

UNITED KINGDOM p.3

". A TOOL FOR RESTORATION : BIO-MANIPULATION IN SHALLOW LAKES •

ZOOPLANKTON AND MACROPHYTE INTERACTION

This paper questions the traditional 'bottom -up approach' and thus traditional restoration methods focused on reducing nutrient levels, most particularly phosphate levels. The lake restoration programme in the Norfolk Broads began in 1980, with the removal of phosphorus from sewage effluents. Despite a 90% reduction in phosphorous to Barton Broad, the lake remained dominated by phytoplankton. ln contrast, this research focuses on top-down processes such as fish- zooplankton phytoplankton interactions and their importance in the restoration of eutrophie lakes.

FEBRUARY 1997

EUROPE p.4

LAKE RESTORATION GUIDE LAUNCH

A Guide to the Restoration of Nutrient Enriched Shallow Lakes, jointly produced by the Broads Authority and the Environment Agency, is supported by the European Commission through its LIFE programme.

SWEDEN p.4

BUILDERS IN DETERGENTS : CITRATES, PHOSPHATES AND ZEOLITES

Over the last few years the laundry detergent market has seen the development of alternative builder systems, moving away from conventional laundry detergents. Numerous studies have shown that the impact on the natural environment of these substitutes is insignificant as a result of this substitution.

AUSTRALIA p.5

THE FIL TER TECHNIQUE FOR SEWAGE EFFLUENT TREATMENT

A filter technique for sewage effluent treatment has been developed in the Murray River Basin in Australia, as a cheaper and more sustainable alternative to existing land treatment systems. lt aims to provide a sustainable and economically viable land treatment system. Nutrient rich effluent for intensive cropping was used, with filtration through the soil to a subsurface drainage system.

UNITED KINGDOM p.6

PUBLIC PERCEPTION AND WATER QUALITY MANAGEMENT

This paper examines the factors which have the greatest impact upon the general public's assessment of environmental quality, and most particularly their perception of water quality. lt shows that those responsible for the management of surface water quality must recognise the need to apply a range of management strategies including a consideration of the public's perception of water quality and the impact of this upon their use of rivers and beaches for recreation and amenity.

SCOPE is a non-commercial, non-profit making European association based in Brussels.

� lts aim is to provide a plattorm for objective and scientific information on the effects of phosphate·containing and phosphate-free detergents on the environment.

SCOPE NEWSLETTER 1 produced by European Communications Unit - 20, rue de l'Arcade - 75008 PARIS - FRANCE -Tel. + 33 1 44 94 80 70

SCOPE : Scientific Committee on Phosphates in Europe - Assoctatton Sans But Lucrattf stse à Bruxelles et soumtse à la Lot du 27 JUin 1921

PHOSPHORUS LEACHING INVESTIGATED IN THE BROADBALK

EXPERIMENT

Movement of P vertically through and out of soil is generally considered to be of little importance, unless soils become P saturated (following heavy manure applications), due to high P fixation capacity of soils. Factors controlling these tosses are generally considered to be related to soil type, pH and weather rather than fertiliser use. These findings have been questioned by data from the Broadbalk Continuous Wheat Experiment at Rothampsted.

For more than 1 00 years plots in the experiment have annually received, either no P, P in farmyard manure (FYM) or in inorganic fertiliser (superphosphate), and now contain a wide range of sodium bicarbonate­extractable P (Oisen-P) concentrations in the plow layer (0 to 23cm). This is, in part, due to differences in P offtakes by wheat given different rates of N fertilisers and grown on soils given the standard rate of fertilisers. The aim of the measurement was to see if significant quantities of P were lost through drainage and the relationship to P concentrations in the plow layer.

lt has previously been demonstrated that about 35% of P inputs to natural waters now come from agriculture in the U.K., 70% in Denmark and 38% in Germany: these percentages but not necessarily the amounts could rise with the increasing control of industrial and municipal discharge.

Drainage water analyses were made on 20 plots on each of five occasions between October 1992 and in February 1994, before and after the installation of a new drainage system (September 1993). Drainage water samples were collected from 20 different plots on 5 occasions, after the drains (at 65cm depth) had been running freely, each time. The drainage water was then filtered. Total particulate P (TPP) was calculated from the difference between TP (total P) and TDP (Total dissolved P). Dissolved organic P (DOP) was calculated from the difference between TOP and DPR. Average Olsen P concentrations in soil were also obtained.

The lowest Olsen-P concentration occurred in the plot which had never received any form of phosphate fertiliser (the nil plot). The next lowest concentrations were found in the plots receiving half the annual standard rate of superphosphate. Plots treated with FYM and the standard rate of superphospahte had more Olsen P ranging from 72mg P kg·1 to 90m Pkg·1• A general trend for plots with higher N rates to have lower Olsen-P concentrations was noted, since the

crop P offtakes were generally greater at the higher rates of applied N.

There was a large variation in both total P concentration and the relative contribution of the P­fractions between the 5 events and the 5 plots. Soils with similar Olsen-P concentrations had comparable P concentrations in the drainage water. DRP was the largest fraction in the drainage water and remained low (<0.15mg L"1) from plots below 60mg Olsen-P kg·1, when there was then a rapid increase in DRP up to the maximum Olsen-P concentration

"""

--,

These findings, shawn on a simple Split Une mode!, imply that below the change point the small lasses were not related to Olsen-P concentrations. Beyond this point P lasses in drainage water were more ·"

closely related to Olsen-P concentrations.

The P leaving the plow layer could have passed to the drains by preferential flow in large cracks through the subsoil or, less likely, rapid transport of P in forms less susceptible to sorption but finally measured as DRP. These processes will be investigated further.

If soil P concentrations continue to increase in the future there could be an enhanced risk of P leaching. This may happen particularly in areas of high livestock density. Further research is necessary in arder to better predict P dynamics, with regard to bath fertiliser efficiency and better environmental protection.

This research has been sited in the ENDS report 263 December 1996, page 10. Quote «ln a study sponsored by the Ministry of Agriculture and the European Commission, Dr Philip Brookes and colleagues have found that excessively fertilised cultivated soils can also leach soluble ----. phosphate. The result was surprising ' Leading experts in the world said it couldn't happen ' Dr Brookes told ENDS. »G.Heckrath, P.C. Brookes, P.R. Pou/ton, and K. W T. Goulding. The Journal of Environmental Quality. Vol 24, no 5, Sept/Oct 1995

ACID LAKES TREATED WITH PHOSPHATE SOLUTION

Lakes acidified by airborne pollutants typically have low biological productivity and support an impoverished flora and fauna. Although they can be neutralised by adding base {lime), the resulting calcium rich water supports animal and plant communities unlike those in natural softwater lakes. This paper examines the results of a 3 year experiment, a pretreatment year, followed by 2 years of fertilisation, in the Lake District.

2

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COMMITIEE

ON PHOSPHATES

SCOPE NEWSLETTER IN EUROPE

lt demonstrates that the modest addition of phosphate to stimulate primary production allows the highly efficient generation of a sufficient ba�e , by nitrogen assimilation to raise the pH of ac1d lake waters. The phytoplankton growth required to bring about this change was modest and did not cause any unacceptable changes in the qualitative composition of the lake's community.

The quantity of base generated depends on. many factors , including the flushing rate of the bas1n, the rate of incorporation into the sediment and gaseous transfers to the atmosphere. Seathwaite Tarn, an upland reservoir, was chosen due to its moderate acidity (pH 5) one main inflow and a gauged outflow.

Most of the phosphorus added was rapidly _ assimulated by growing phytoplankton, p�rticularly

'nanoplankton', which were consumed 1n large numbers by filter feeding crustacea, accelerating the rate at which the fixed carbon is deposited in the deep sediment.

The treatment will work best for lakes with a residence time in excess of a year. A modest initial acidity and a sustained loading of nitrogen from the atmosphere or catchment is also desirable. lnducing small increases pH (0.5 in this case) is worthwhile, since it may markedly reduce the metal content of polluted waters. Poor productivity in acid waters is usually associated with poor supplies of phosphorus. ln addition to the increase in zooplankton in Seathwaite tarn there have already been signs of an improved growth rate of the seant brown-trout population.

ln practical terms it is difficult to diss.olve calc!um carbonate, whilst phosphate can be eas1ly added 1n a concentrated form. ln this experiment 5.9m3 of phosphate solution was added, whereas it would

�- have taken 34 tonnes of calcium to obtain similar results. Moreover the phosphorus solution does not result in an unnatural chemistry and the pH is restored to pre-acidification levels rather than to unnaturally high levels. The addition of phosphate can clearly be cost effective, particularly if there is ultimately considerable recycling of phosphorus.

This study shows that it is possible for phosphate to have beneficiai environmental effects and that eliminating phosphate may increase problems of low productivity and acidity. lnstitute of Environmental and Biological Sciences, Lancaster University. lnstitute of Freshwater Eco/ogy, Ambleside. W.Davidson, D.G.George & N.J.A.Edwards. Nature vo/37712 Oct 1995

A TOOL FOR RESTORATION : BIO-MANIPULATION IN SHALLOW LAKES -THE

FISH-ZOOPLANKTON INTERACTION

This paper questions the traditional 'bottom -up approach' and thus traditional restoration methods focused on reducing nutrient levels, most particularly phosphate levels. The lake restoration programme in the Norfolk Broads began in 1980, with the removal of phosphorus from sewage effluents. Despite a 90% reduction in phosphorous to Sarton Broad, the lake remained dominated by phytoplankton. ln contrast, this research focuses on top-down processes such as fish- zooplankton -phytoplankton interactions and their importance in the restoration of eutrophie lakes.

Grazing by zooplankton can r�duce chlorophyll a concentrations. However predat1on by planktlvo�ous fish during the summer prevents such populations from developing in most of the lakes studied (in the Norfolk Broads).

lt has been shown by artificially reducing these �sh populations from sorne of the�e lakes, the result�ng increase in zooplankton grazmg has reduced the chlorophyll a concentration creating �lear wate:r a�d allowing the establishment of aquat1c vegetat1on 1n the lakes.

This biomanipulation provides a good tool which could be used by lake managers (see a_Jso t�e following article on best ma!lagement pract1�es) 1n the planning of the restorat1on of lakes wh1ch a�e plankton dominated instead of nutrient removal. Th1s method is more effective in shallow lakes as the zooplankton may be able to switch to sediments as an alternative food source wh en the phytoplan kton population is reduced .

lt has also been demonstrated that in unmanipulated broads there is a significant positive correlation between large grazing zooplankton and macrophyte biomass. ln addition the least number of fish were found associated with dense macrophytes, corresponding with extremely low predation pressure. lt is clear that macrophytes provide a refuge for grazing zooplankton . and thus a _long_ term accumulation of nutnents may ass1st 1n the maintenance of low algal standing crops. These macrophyte dominated lakes have a greater proportion of pike to prey species than plankton dominated lakes.

Water for chemical analysis and zooplankton samples from 3 lakes (Upton Broad, Hoverton Litte Broad and a fish enclosure in a nearby isolated bay) were collected regularly during 1992/3. Fish removals

3

Association Sans But Lucratif

were carried out using non destructive techniques, mainly electrofishing. Fish removal was thought to have reduced the fish population by at least 90%.

Hoveton Little and Upton Broads provide good examples of the contrasts seen in the plankton of the Broads. ln Hoveton Little Broad D.hyalina only occurs for a short period associated with a spring clear water phase. Clearly planktivorous fish in this kind of environment rapidly reduce the populations of these larger cladocerans, leaving the zooplankton dominated by smaller species such as B.longirostris in the summer.

ln Upton Broad moderate populations of D.hyalina occur Jan - July, when macrophytes become weil established in the lake, and weed associated cladoceran species are found. ln the absence of planktivorous fish in this lake and in the fish enclosure, large cladoceran species are predominant throughout the year.

When planktivorous fish were removed from these lakes, such as in the fish enclosure, it is clear that despite zooplankton population cycles low chlorophyll concentrations could be maintained. This form of biomanipulation seems to be a practical way of creating clear water conditions provided the control of the fish population continued.

ln many other European lakes biomanipulation carried out on only once or twice has led to a shift in community structure of the lake, maintained over many years. This was almost always in association with the rapid development of aquatic vegetation. The mechanism is still unclear although vegetation uptake and the physical nature of the plants are thought to play a major role. The role of piscivorous fish in determining lake structure is also unclear. Initial observations support the view that high pike biomass in relation to planktivorous fish is linked to macrophyte dominated lakes and restructuring of the fish community is likely to be an essential final step in the permanent restoration of these lakes.

lt has been shawn in published relationships that as far as biomass and nutrient supply are concerned ali lakes tend to follow the same general curve. Concerning summer chlorophyll a and total phosphorous the data can be divided into two categories : those lakes dominated by phytoplankton, and those by macrophyte. Biomanipulated lakes fall between these two groups, and suggest that within a range of phosphorous concentrations either plankton or macrophyte states can form stable communities without any further artificial intervention.

A simple nutrient supply reduction to a lake will not necessarily result in the desired reduction in algal growth, except if the food webs are able to restructure. Biomanipulation can be considered as a

way to assist in this process, and it may be an essential step in the restoration of shallow lake

G.L.Phillips, M.R.Perrow & J.Stansfield. Aquatic predators and their Prey Chapter 22 - 1996.

BEST MANAGEMENT PRACTICES LAKE RESTORATION GUIDE LAUNCH

A G uide to the Restoration of Nutrient Enriched Shallow Lakes, jointly produced by the Broads Authority and the Environment Agency, is supported by the European Commission through its LIFE programme. _,

The first comprehensive handbook linking up-to-date science with practical techniques to solve one of the environment's most pressing problems has been launched.

The guide outlines how to deal with eutrophication. lt is aimed at lake managers across Europe, and includes a step-by-step strategy for restoration based on a sound ecological approach. The Environment Agency is developing a strategy for handling eutrophication and will be consulting organisations with a particular interest. A Guide to the Restoration of Nutrient Enriched Shallow Lakes. Brian Moss, University of Liverpool, Jane Madgwick, the Broads Authority, Geoffrey Philips, the Environment Agency. Jan 1997. ISBN 0-948119-29-2

BUILDERS IN DETERGENTS : CITRATES, PHOSPHATES AND ZEOLITES

Over the last few years the laundry detergent market has seen the development of alternative builder systems, moving away from conventional laundry detergents. Numerous studies have shown that the impact on the natural environment of builders is insignificant. Citrates, phosphates and zeolites were studied : none were found to have taxie effects, and no negative effects on the environ ment were fou nd. lt is tobe noted that phosphate free detergents contain many more surfactants which may have a higher rate of toxicity.

Phosphates are most efficiently removed during advanced waste water treatment, thus allowing more scope for recycling. Citrates decay biologically in the waste water treatment implying no burden to the recipient.

VATTEN 52:197-203. Lund Andreas Bjorklund, Stefan Mattsson and Gunnar Karlsson.

4

THE FIL TER TECHNIQUE FOR SEWAGE EFFLUENT TREATMENT

A filter technique for sewage effluent treatment has been developed in the Murray River Basin in Australia, as a cheaper and more sustainable alternative to existing land treatment systems. lt aims to provide a sustainable and economically viable land treatment system. Nutrient rich effluent for intensive cropping was used, with filtration through the soil to a subsurface drainage system.

The Environment Protection Agency (EPA) promotes sewage effluent treatment by land application to reduce nutrient and other pollution of water bodies and to minimise waste generation. However in certain areas of Australia land treatment effluent is often less economical than other treatment techniques due to the cost of winter and wet weather effluent storage on high value urban lands. The low permeable clay soils dominating the urban areas of eastern Australia are also prone to waterlogging and salinisation which may reduce the long term sustainability and economie viability of the effluent application sites. A need was identified to develop a technique adapted to overcome these problems.

FIL TER (Filtration and lrrigated cropping for Land Treatment and Effluent Reuse) combines the usage of nutrient-rich effluent for intensive cropping with filtration through the soil to a sub-surface drainage system. This is carried out during periods of low growth activity and high rainfall, thus eliminating the need for effluent storage.

The system is regulated to ensure adequate nutrient ,_ · removal and so produces low-nutrient drainage

waters. This filtration phase could be followed by a cropping phase to remove any nutrients stored in the soil, if necessary, thereby ensuring a sustainable system. Specifie combinations of filtration and cropping phases used depend on site conditions.

Total phosphorus and total nitrogen concentrations in the drainage waters were reduced weil below EPA target limits of 1.0mgL·1 and 15mgL·1 respectively. Total phosphorus and total nitrogen loads were reduced by 96% and 85% respectively.

The effluent showed presence of blue-green algae whilst the drainage water did not, thanks to the increase in the N :P ratio (from 3 to 23), coherent with previous research which has showed the threshold to be approx. 12.

The crops selected for the plots were relatively waterlogging and moderately salinity tolerant, so crop yields and nutrient removal rates during the filtration

phase were comparable to those obtained overseas in weil managed land treatment systems.

Another potential use for the system has been identified in a separate trial involving spiking the effluent with the full range of pesticides used in agricultural enterprises in the area. Pesticide loads were reduced by more than 98%. Modified FIL TER systems may be used to treat commercial and industrial effluents containing heavy metals and chemicals, feedlots, piggeries and dairies.

Water November!December N.S.Jayawardane & J.B/ackwe/1

1996 pp18-21.

PUBLIC PERCEPTION AND WATER QUALITY MANAGEMENT

This paper examines the factors which have the greatest impact upon the general public's assessment of environmental quality, and most particularly their perception of water quality. lt shows that those responsible for the management of surface water quality must recognise the need to apply a range of management strategies including a consideration of the public's perception of water quality and the impact of this upon their use of rivers and beaches for recreation and amenity.

The general public's initial perception of river and coastal environmental quality is often based solely upon visual and odorous characteristics. These factors bear very little relation to actual physico­chemical or biological water quality.

ln recognition of the importance of these factors to the general public the National Rivers Authority (NRA), the principal regulator of water quality in England and Wales, has developed a new General Quality Assessment (GQA) scheme, which includes consideration of the aesthetic impact of pollution parameters for the first time.

Research was carried out 1992-1994 to evaluate the importance of individual water quality impairment parameters ; foaming, litter, coloured effluents, and sewage derived waste products to perceived water quality and the use of rivers and beaches for recreation and amenity.

ln theory the presence of sewage derived contaminants should have the greatest negative impact on the enjoyment of a visit to a river or beach. However people failed to recognise sewage derived products, either because they are not familiar with them or because of an unwillingness to mention specifie products. Solid waste contaminants were

5

more disturbing in the water than on the beach or the banks of a river. Single items of derived sewage waste seemed to have a greater impact than a conglomeration of items. A large proportion of the public did not identify these products as coming from the water.

water quality. This highlights the importance of a weil thought out strategy in any public discussion of factors such as phosphate in the environment.

ln conclusion it can be seen that there is a gap between the « real » versus « apparent » effect in

Public Perception and Water Qua/ity Management. Margaret A. House : Middlesex University, Queensway, Enfield, U.K.

The SCOPE Newsletter is produced by the SCIENTIFIC COMMITIEE ON PHOSPHATES IN EUROPE, a non commercial, no profit-making association (Association Sans But Lucratif) based in Brussels. The association includes international groups headquartered in Belgium, France, Spain, Sweden and the UK, producers of a wide variety of detergent ingredients including phosphates. lts aim is to provide a platform for objective and scientific information on the effects of phosphate-containing and phosphate-free detergents on the environment. The SCOPE Newsletter is open to input from its readers across Europe and we welcome ali comments or information., Contributions from readers are invited on ali subjects conceming phosphates, detergents, sewage treatment and the environment.i Y ou are invited to submit scientific papers for· summary to send comments on the studies mentioned in this Newsletter or othe scientific or technical news.

For more information, please contact : E.C.U. (European Communications Unit) - who produce this Newsletter for 20, rue de l'Arcade, 75008 Paris, France, Tel. + 33 1 44 94 80 70 Fax +33 1 44 94 81 01 E-mail ecu@net.asi.fr

The SCOPE NEWSLETTER is also available on INTERNET at : http://www.asi.fr/scope

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SCIENTIFIC ----- ---- ----- - --- � �-�-��

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NORWAY p.2

NORWEGIAN RESEARCH PROGRAMME BASED ON NUTRIENT INPUT INTO THE SEA The state owned conglomerate Norsk Hydro bas launched a five year research programme called Maricult (funded in part by the European Commission) designed to consider the cultivation of marine ecosytems. It will study the opportunities and constraints for a more comprehensive use of the oceans in order to improve our prospects for a larger, yet sustainable harvest of marine resources in the future in an environmentally acceptable way involving the addition of nutrients.

SPAIN p.2

A REAL LIFE STUDY ON THE CONSUMER'S SHOPPING BASKET

An interesting study was carried out on nine different conventional and compact detergents, bought in a supermarket in Spain, containing STPP or other builders, used for washing textiles. 5 were conventional, of which 3 contained STPP ; and 4 were compact, of which 2 contained STPP.

GERMANY p.3

BIO REMEDIA TION OF AN OLD FUEL OIL­CONTAMINATED SITE USING HEXAMETAPHOSPHATE

Groundwater is often found to be contaminated with various organic chemicals whereby heterotrophic bacteria dominate. Phosphate is a required electron acceptor, an essential nutrient, and an important limiting factor of hydrocarbon degradation in bioremediation.

This case concerns contamination, 40-50 years ago, by a leaking pipeline, of 15 000-17 000 L. Most of the oil tloating on the groundwater was removed in the 70's ; the pollution now lies 4-9m below ground level.

AUSTRALIA p.3

ANAL YSIS ON THE TOXICITY OF COMMERCIAL AVAILABLE LAUNDRY DETERGENTS ON NATIVE FRESHWATER CERIODAPHNIA DUBIA

RICHARD

Tests were carried out on 20 Australian, and 4 British laundry detergents, purchased in Sydney during June 1994, to determine the relative impact of phosphate containing and phosphate free formulations in view of the lack of knowledge on their toxilogical effects on the Australian environment

NORWAY p.3

INPUTS TO THE OCEAN AND RESULTING POLITICAL DEMAND FROM THE SCIENTIFIC COMMUNITY LEADS TO DESIGN OF A 3D MO DEL

This paper describes a model to calculate mass and volume transport and primary production throughout the North Sea. This was the first time su ch a 3D baraclinic hydroclynamical model bad been coupled to a chemical biological model in order to better understand these parameters. In response to political pressure to understand the impact of a 50% reduction of nutrient input, Morten D. Skogen et Al. ran the model for the year 1985 with specified time series of riverine and atmospheric inputs and they reran it with a 40% reduction. The authors conclude it would be a useful tool for political and environmental planning.

U.K. p.4

CLASSIFICATION AND ASSESSE MENT OF WATER QUALITY IN LAKES

This paper studies the way water quality can be assessed in standing waters ; a subject which bas, until recently, with the introduction of European legal requirements, attracted very little attention. A scheme is described to assess, classify and monitor water and ecological quality in standing waters greater than 1ha in area in England and Wales, though is normally applicable to North West Europe.

SCOPE is a non-commercial, non-profit making European association based in Brussels.

Ils a1m is to provide a platform for objective and scientific information on the effects of phosphate-containing and phosphate·free detergents on the environ ment

SCOPE NEWSLmER

produced by European Communications Unit- 20, rue de l'Arcade- 75008 PARIS- FRANCE- Tel.+ 33 1 44 94 80 70

SCOPE : Scient1f1c Corr�m�ttee on Phosphates in Europe· Association Sans But Lucratif sise à Bruxelles et soum1se à la Lo1 du 27 Juin 1921

NORWAY

NORWEGIAN RESEARCH PROGRAMME BASED ON NUTRIENT INPUT INTO THE SEA

The state owned conglomerate Norsk Hydro bas launched a five year research programme called Maricult (funded in part by the European Commission) designed to consider the cultivation of marine ecosytems. It will study the opportunities and constraints for a more comprehensive use of the oceans in order to improve our prospects for a larger, yet sustainable harvest of marine resources in the future in an environmentally acceptable way involving the addition of nutrients.

Overfishing bas resulted in reduced global harvests of major fish stocks in the recent past . The problems associated with managing these stocks bas been put on the national agenda.

The richest fishing grounds are found where there is a continuous flow of nu trient rich deep water to the surface resulting in short, efficient food webs. Typical areas cao be found off the coast of Chile and Namibia. These « upwelling areas » comprising only 0.1% of the ocean surface, produce 50% of global fish production. This clearly indicates a potential for increased production in marine ecosystems.

Maricult raises the question : « Cao we learn how nature creates these areas of high biological productivity, and are we able to imitate this artificially in other coastal areas ? »

The research programme emphasises studies of the effects of dosages of plant nutrients, namely nitrogen and phosphorus, at concentrations found naturally in upwelling are as.

The experiments are to be conducted in areas of limited size in marine food webs and seaweed areas and involve the supply of nutrients in controlled conditions : their aim being the defmition of the conditions leading to a useful productivity that cao be harvested

Preliminary studies show that although introducing desired species on a large scale, plus other biological aimed initiatives, was not enough, the introduction of fry would increase the chances of success if the fry's food supply increased correspondingly, particularly at the youngest stages. This is only possible if an adequate amount of nutrients is supplied by artificial upwelling or direct application of mineral fertilisers

Nutrients will only be added where an increased productivity of plankton is desired. The composition and the amounts must match both the fluxes which occur in naturally high productive areas and the natural requirements, in order to prevent the growth of harrnful and undesirable algae.

A large nutrient supply may increase both fish production and sediment rate, leading to an advanced an accelerated carbon accumulation rate on the seabed. Even if at present it is difficult to imagine artificial fertilisation of the sea as a viable prospect for removing C02 from the atrnosphere, it may weil become a future option.

The results of this project will contribute significantly to highlight and clarify important aspects of the environmental impact of nutrient discharge into marine systems and thus increase our knowledge on the effects of nutrient dosage and biological indicators of eutrophication.

The Maricult Research Programme. Hydra Porsgrunn Industria/ Park P.O. Box 1 JO, 3901 PORSGRUNN.

SPAIN

A REAL LIFE STUDY ON THE CONSUMER'S SHOPPING BASKET

An interesting study was carried out on nine different conventional and compact detergents, bought in a supermarket in Spain, containing STPP or other builders, used for washing textiles. 5 were conventional, of which 3 contained STPP ; and 4 were compact, of which 2 contained STPP.

Ail samples were subjected to a treatrnent reproducing a typical European textile-washing process after which the following parameters were measured

(i) total suspended solids (TSS) (ii) dissolved organic carbon (DOC) (iii) chemical oxygen demand (COD)

The three main aims of the study were :-

(i) the experimental determination of chemical parameters related to the aquatic environment : it was found that the P-based formulations (both conventional and compact) contain less TSS, and have lower COD and DOC than P-free formulations. Only P-based washing powders irnproved washing performance in compact form ; moreover, a smaller amount of detergent was needed for equivalent soil removal, implying a smaller release of the detergent into the aquatic environment.

(ii) experimental determination of detergency for each detergent category : common maximum soil removal was 40% on cotton and 48% on polyester/cotton. Detergency on cotton fabric of 40% the calculated dose was 8.8,10, 4.4, and 10.6g/L, for P-based conventional, P-free conventional, P-based compact, and P-free compact respectively. Similarly the dose was 11.9, 10, 4.2 and 10.6g/L, respectively on polyester/cotton.

2

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(iii) evaluation of the environmental impact at equivalent detergency performance : as far as results of chemical loading to the environment is concerned, assuming an equal detergency performance for a typical wash (20L), detergent load, surfactant load, COD, DOC and particularly TSS are much smaller for P-based than P-free detergents, especially P-based compacts.

After examining these three points it was concluded that the use of compact detergents containing STPP implies a lower environmental impact than other detergents tested, in terms of both a reduced generation of sludge residues and a reduced organic load in sewage works.

Comparative Study of Conventiona/ & Compact detergents. J.Sanchez Leal, L.Perez, J.Ribosa, M. T. Garcia & J.J. Gonzalez. Centro de lnvestigaci6n y Des arro llo (CJSC) Barce/ona, Spain.

JAOCS, Vo/.73, 27-30 no 1 (1996)

GERMANY

BIOREMEDIATION OF AN OLD FUEL OIL­CONTAMINATED SITE USING

HE�TAPHOSPHATE

Groundwater is often found to be contaminated with varions organic chemicals whereby heterotrophic bacteria dominate. Phosphate is a required electron acceptor, an essential nutrient, and an important limiting factor of hydrocarbon degradation in bioremediation.

·

This case concerns contamination, 40-50 years ago, by a leaking pipeline,of 15 000-17 000 L. Most of the oil noating on the groundwater was removed in the 70's ; the pollution now lies 4-9m below ground level.

The in situ remediation design consists of 2 infiltration wells, production wells, plus a groundwater processing plant. Before infiltration, hydrogen peroxide and nitrate were added to the reinfiltrated water to meet the electron acceptor demand, plus phosphate to meet nutrient demand.

Initial results suggested that phosphorus was the limiting factor for heterotrophic bacterial activity. lt is probable that the phosphate stopped the limitation and oxygen was used in and next to the infiltration wells. However, during the use of diphosphate, problems occured with the precipitation of insoluable phosphate salts and thus plugging of the infiltration wells and the surrounding aquifer occurred.

After 2 months the phosphorus source was stopped, the wells regenerated with H202 and acid, then 6 weeks later was replaced by sodium hexametaphosphate. This

eliminated problems of precipitation and plugging in the infiltration wells. For the fust time a phosphorus supply for the whole contaminated area was observed.

Although ail the work to date on polyphosphates in bioremediation bas concentrated on tripolyphosphates, this study showed the superiority of polyphosphate over orthophosphate on a field scale. It was also found that sodium hetamexaphosphate is superior over commonly used phosphates in transporting phosphorus over long aquifer distances.

Martin Steiof!Wolfgang Dott.Applied Bioremediation of Petro/eum Hydrocarbons (30 1-309)

AUSTRALIA

ANAL YSIS ON THE TOXICITY OF COMMERCIAL A V AILABLE LAUNDRY DETERGENTS ON

NATIVE FRESHWATER CERIODAPHNIA DUBIA RICHARD

Tests were carried out on 20 Australian, and 4 British laundry detergents , purchased in Sydney during June 1994, to determine the relative impact of phosphate containing and phosphate free formulations in view of the lack of knowledge on their toxilogical effects on the Australian environment.

The detergents were classified according to their chemical composition using a 2 way classification system, whereby each product belonged to 2 categories :-

(i)high phosphate (HP), containing more than 5% phosphorons on a weight to weight basis (w/w) (ii)low phosphate (LP) containing 1-5% phosphorons (w/w) (iii)phosphate free (PF) containing less than 1% phosphorons (w/w) these categories were further subdivided into :­

(iv)containing neither enzymes nor zeolites (NoE & NoZ) (v) containing enzymes (E) (vi) containing zeolites (Z) (vii) containing enzymes & zeolites (E & Z)

Australian cladocera Ceriodaphnia dubia was chosen as the test species since it is representative of the zooplankton which graze on algae and help prevent the development of toxic algal blooms. cladocerans were exposed to 5 concentrations of each detergent, plus a control, which were randomly placed in each test vessel and covered with cling film. Each treatrnent in each test was triplicated and each test repeated 3 times. The tests were terrninated after 48 hours. A further quality control measure was taken using the Environment Canada methodology ( 1990) to determine if detergent toxicity data

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was accepted or rejected. Only data passing this test was used.

As far as the results are concerned it must be borne in mind that the percentage of the recommended dose (%RD) toxicity data were likely to contain greater error than the concentration toxicity (mg!L) data since recommended doses were often vague and it is questionable if consumers actualiy use these doses.

It was found that the most toxic Australian detergent was approx. 35 & 25 (mg!L & %RD respectively ) times more toxic than the least toxic. The toxicity values obtained were similar to th ose deterrnined by Ankley et al ( 1990) for U.S. detergents and individual surfactants tested on a U.S. cladoceran.

Ali 4 U.K. detergents were found to have medium toxicity (1 mg!L<EC50<10mg!L), 15 of the Australian detergents were classed as having low toxicity (EC50<10mg!L) and 5 were of medium toxicity (1mg!L<EC50<10mg/L). These differences were not statistically significant.

The contingency analysis showed that toxicity class is independent of phosphate concentration, the presence or absence of enzymes,the presence or absence of enzymes and zeolites combined and various combinations of these. The authors concluded that not only phosphates, but also other detergent components could contribute to toxicity , including surfactants (one of the most toxic, Canton &

Slooff 1982), chelates and enzymes.

The results of ali the analyses underlined that it is not possible to generalise about the toxicity of detergents based on the criteria used to classify the detergents in this study, since there is a large variability in the toxicity of detergents belonging to each class.

It was concluded that the explanation of the differences in toxicity was likely to lie in the chemical composition of individual detergents. The important components contributing to toxicity could include surfactants, enzymes and chelates. The second stage of this research project will consider which of these components are predominantly responsible for the toxicity of Australian detergents.

Michael St. J. Warne. Australasian Journal of Exotoxicity Vol!,pp 127-135, 1995

NORWAY

INPUTS TO THE OCEAN AND RESULTING POLITICAL DEMAND FROM THE SCIENTIFIC

COMMUNITY LEADS TO DESIGN OF A 3D MO DEL

This paper describes a model to calculate mass and volume transport and primary production throughout the North Sea. This was the first time such a 3D baraclinic hydroclynamical model bad been coupled to a chemical biological model in order to better understand these parameters. In response to political pressure to understand the impact of a 50% reduction of nutrient input, Morten D. Skogen et Al. Ran the mode) for the year 1985 with specified time series of riverine and atmospheric inputs and they reran it with a 40% reduction. The authors conclude it would be a useful tool for political and environmental planning.

The NORWECOM (NORWegian ECOlogical Model System) presented in this paper focuses on· the 1995 modeliing of mass and volume transport and primary production throughout the North Sea.

Two factors contributed to the development of this : inputs to the ocean and the resulting political demand to the scientific community to clarify the situation; and the importance of understanding the primary production process because of it's importance as a possible regulating mechanism for the fish production.

In order to obtain realistic biological results, the coupled chemical biological model system was based on a sophisticated 3 dimensional physical model that was able to represent the vertical exchanges realistically.

This madel is discretized in a 20 x 20 km grid with 1 1 vertical layers which foliow the bottom topography. The madel calculates ali the P.C.B. prognostic variables every 15 minutes. It is strongly dependant on two physical constants:

a minimum value for the vertical eddy viscosity/diffusion coefficient

a dimensionless horizontal diffusion constant

The 7 chemica1 biological pragnostic variables are :

• inorganic nitrogen (such as nitrate and ammonia)

• inorganic phosphorus (phosphate)

• inorganic silicon (silicate)

• detritus (dead organic matter)

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• diatoms

• flagellates

• lightlturbidity

The compiling involves 4 physical variables :-

• subsurface light

• hydrography

• the horizontal movement of water masses

• the vertical movement of water masses

The mode! is based on the following hypotheses

IN EUROPE

• nutrients are added to the system from the many rivers and from the atmosphere (only nitrate)

• nitrogen and phosphate are also reglemented from the dead algae, detritus at a constant rate

• no zooplanktoon eating the algae and no <<particle» bottom settlement and resuspension are incorporated.

The analysis of the data demonstrates a strong coherence between model results and existing litera ture ( with sorne discrepancies in the North) as weil as a strong seasonal variation in production of diatom and flagellate blooms. The balance between diatoms and flagellates is clearly linked to silicate as a lirniting seasonal factor.

For the flagellate bloom the authors also observed a strong correlation between the plankton correlation and the available phosphorous, nitrogen being a nutrient.

Blooms of toxic algae have dramatically increased over the past few years. The mode! was thus rerun based on political decisions to reduce nutrient input by 50% around the North Sea, with the hypothesis of reducing initial conditions by the same percentage.

This reduction only affected., as predicted (see above) the flagellates, with more than a 25% reduction in local regions, and an overall 5-10% reduction annually (with sorne uncertainties in the mode! due to Jack of resolution in the çoastal region).

However, the mode! can not be considered to be 100% accurate since various phenomenon can generate discrepancy in the simulation, eg. sensitivity of the model to initial conditions, annual calculation conception of the model, the importance of the recycling of nutrients, lack of sedimentationlresuspension process as a component of the mode!.

Despite these limitations the potential of using this kind of model, to study, for example, reduced deposition of

nutrients to the North Sea, makes them a useful tool in political and environmental planning.

Skogen, Svendsen, Bemstsen, Aksnes & U/vestad. Esturine, Coastal and She/f Science (1995) 41, pp. 545-565.

U.K.

CLASSIFICATION AND ASSESSEMENT OF WATER QUALITY IN LAKES

This paper studies tbe way water quality can be assessed in standing waters ; a subject which bas, until recently, with tbe introduction of European legal requirements, attracted very little attention. A scbeme is described to assess, dassify and monitor water and ecological quality in standing waters greater tban lba in area in England and Wales, tbougb is normally applicable to North West Europe.

Thirteen bydrological, chemical and biological variables are used to cbaracterise the water body, these variables being the key indicators of the state of eutropbication, acidification, salinisation, and infilling of a water body :-

• lake volume

• maximum depth

• conductivity

• Secchi dise transparency

• pH

• total alkalinity

• calcium ion concentration

• total N concentration

• win ter total oxidised inorganic nitrogen ( effectively nitrate) concentration

• total P concentration

• potential maximum cblorophyll a concentration

• a score based on the nature of the submerged and emergent plant community

• the presence or absence of a fish community

The scheme is not, however, a closed one and other variables could be included wben necessary, and when appropria te reference data becomes available ( eg.oxygen profile, benthic invertebrate comrnunity, phytoplankton comrnunity and fish comrnunity).

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Standing waters are classified- within the scheme in a value-or-state change system in wbicb the contemporary values of the variables are compared with a reference baseline state and then classified according to percentage ebange from this baseline. A mean percentage ebange in ali variables can be calculated or the variables can be sub­grouped to indicate change in the directions of eutrophication, acidification, infilling or potentially any other factor if the relevant variables are included and can be determined in the baseline. The baseline state also provides an objective reference for determining water quality objectives for given water bodies.

The baseline state is the one wbicb reflects a sustainable agricultural land-use of the catchment and thus a consequent quality of the water body, determined by the catchment's natural topography, clirnate and geology but in the absence of sewage effluent untreated to remove phosphorous. Since the Second World War land-use bas been increasingly determined by economie and technological factors, with natural features taking second place.

The Annual Agricultural Censuses allow reconstruction of aspects of the water chemistry of appropriate baseline states for individual lakes or lakes grouped in uniform regions. Appropriate nutrient variables (total N and total P concentrations) can be predicted to within a few percent, as can retention time and conductivity and from these variables the others listed can be calculated. Comparisons of change can then be made for any contemporary data set.

The scheme, incorporating a ranking scheme for aquatic plants, bas been designed for use on lakes grea ter than 2ha in England and Wales and for others of significant amenity or conservation interest. It has been pre-tested on 90 lakes, the results showing a higb degree of change in British standing waters. Results are consistent with studies carried out with other methods. The system will be easy to computerise, allowing autornatic baseline calculations and comparisons.

By Brian MOSS, Penny JOHN ES and Geoffrey PHILLIPS. Bio Rev. (1996) 71. pp 301-339

The SCOPE Newsletter is produced by the SCIENTIFIC COMMIITEE ON PHOSPHATES IN EUROPE. a non commercial, non profit-making association (Association Sans But Lucratif) based in Brussels. The association includes international groups headquanered in Belgium, France, Spain, Sweden and the UK, producers of a wide variety of detergent ingredients including phosphates. lts aim is to provide a platform for obJective and sc1entific information on the effects of phosphate-containing and phosphate-free detergents on the environment. The SCOPE Newslctter is open to input from its readcrs across Europe and wc wc !come ali comments or mformation. Contributions from readers are invited on ali subjccts conccming phosphates, detergents, scwage treatment and the environ ment. Y ou arc invned to submit scientific papcrs for résumé, to send comments on the studies mentioncd in this Ncwslener or other scientific or technical news. For more information, pl case contact:/ E.C.U. (European Communications Unit)- who produce this Ncwslener for SCOPE-20, rue de l'Arcade, 75008 Paris, France, Tel.+ 33 1 44 94 80 70 Fax +33 1 44 94 81 01 E-mail ecu@net.asi.fr

The SCOPE NEWSLETTER is also available on INTERNET at : http://www.asi.fr/scope

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NUMBER EIGHTEEN

THE NETHERLANDS 2· 2

The effect of pollution on phytoplankton dynamics in the River Meuse The c o r r e l a t i o n between phyt o p l ankton development, and chemica l and physical characteristics of water extracted from the River Meuse has been examined. The River Meuse is

JULY 1996

However, no result on this issue coutd be obtained since no increase in P-concentration had appeared due to fish farming activities. The authors concluded that fish production could be multiplied by 200 without affecting the lakes' trophic condition.

� - described as highly eutrophie and carrying a persistent load of toxic compounds. Results of the study show that the phytoplankton growth rate may be related to a high toxicity. An approach incfuding both functional and structural parameters is recommended for rehabilitation programmes.

GERMANY p. 4

Opportunities and constraints in t h e recycling of nutrients

This a rticle addresses the question of nutrient recycling. Dr. Joachim Lammel, from the Centre f or Plant Nutrition and Environmental Research in Hanninghof. Germany, studies the different components of the recycling nutrients issue (historical, sociological, economical and technical) .

FRANCE 2·2

Evaluation of phosphorus f r om point sources on a catchment area scale Researchers from the savoie region in France, have proposee! a new mode! for evaluating phosphorus from point sources in a catchment area. The madel distinguishes phosphorus coming from the area itseH, sources coming from upstream, and diffuse sources. The information collected from the application of the mode! should contribute to developing and adjusting eutrophication control strategies in sensitive areas.

NEW BOOK 2· 3

Phosphorus in the global environment The Scientific Committee on Problems of the Environment (not to be confused with the organisation SCOPE which edits this newsletter) publishes a compilation of articles on transfers, cycles and management of phosphorus in the environment.

SWEDEN 2· 4

Impact of fish farming on lakes' phosphorus concentration An extensive research project has been conducted in Sweden to evalua1e the impact of fish farms on eutrophication phenomenon in lakes (see also our previous Newsletter). One of the study's objectives was to see whether phosphorus emissions from rainbow trout farms could be used to reduce mercury and radiocaesium levels in the lakes' fish.

AUSTRALIA 2·5

A new process reduces the amount and cost of c hemicals used for phosphorus removal from waste water. Alum sludge might contribute to lowering both cost and amount of chemicals used for removing phosphorus from waste water. If the trials conducted by the Centre for Wastewater Treatment at the University of New South Wales at Bowral are successful, this technique could be used throughout Australia.

NORWAY 2· 6

Assessment of cost e f fic ie ncy a nd sustaina b ility of wastewater treatment processes at the University of Trondheim. Cost efficiency and sustainability of different commonly used wastewater treatment techniques were evaluated. Results show that among the methods assessed, chemical treatment atone and advanced treatment with chemical pre-treatment rank first with respect to bath criteria However, the author notes that municipal wastewater treatment equipment is often chosen according to national or international treatment standards rather than the quality and self purifiCation capacity of the local receiving water.

SCOPE is a non-commercial, non-profit ma king European association based in Brussels.

lts aim is to provide a platform for objective and scientific information on the effects of phosphate-containing and phosphate-free detergents on the environment.

SCOPE NEWSLETTER

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produced by European Communications Unit- 81, rue François Mermet- 69160 TASSIN - FRANCE -Tél. (33) 78 34 23 39

SCOPE : Scientific Committee on Phosphates in Europe -AssoCiation Sans But Lucratif sise à Bruxelles et soumise à la Loi du 27 juin 1921

THE NETHER LANDS

THE EFFECT OF POLLUTION ON PHYTOPLANKTON DYNAMICS IN THE

RIVER MEUSE

The correlation bet ween phytoplankton development, and chemical and physical characteristics of water extracted from the River Meuse has been examined. The River Meuse is described as highly eutrophie and carrying a per s is tent load of t oxic compounds. Resulta of the study show that the phytoplankton growth rate may be related to a high toxicity. An approach including both functional and structural p a r a m e t e r s is r e c o m mended for rehabilitation programmes.

The River Meuse is described as a typical nutrient rich lowland river with relatively high plankton productivity. Previous studies have shawn a strong relationship between the presence of toxicants and the decline of species in the river.

Twenty litre water samples were collected at 8 points along the river in February, April, June, August, October and December 1993. The samples were taken to a laboratory where they were maintained at their original temperature. The following parameters were measured :

Biological parameters:

Chlorophyll A concentration Contribution of functional groups to Chloropyll A Rate of carbon fixation by phytoplankton Bacterial growth

Physical and chemical parameters:

Dry weight of suspended matter Dissolved reactive phosphate Ammonium ions Nitrate Nitrite Dissolved reactive silicate

Toxicity of polar organic compounds concentrated by XAD resin and measured with the Microtox test system.

The study revealed a relatively law Chlorophyll A concentration in the River Meuse in comparison wi1h other large rivers. This observation cannot be explained by nutrient depletion. Phosphate and

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ammonium concentrations are very high and cannat therefore be limiting in any part of the river. The hypothesis of a regulation by zooplankton grazing has also been considered. High zooplankton densities were correlated with declining phytoplankton concentration in April, June and August.

ln water samples collected in locations with a high content of organic substances, the low phytoplankton growth rate supported the idea of a strong correlation between the presence of toxicants and the inhibition of plankton productivity. The presence in abundance of light and nutrients at these locations also upholds this hypothesis.

Due to uncertainties conceming the effiCiency of the XAD-concentration procedure, the authors indicate

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that the interaction between organisms and pollutants ""·

may be under-estimated in the results. A possible impact of the pollutants on the plankton species composi1ion is also suggested.

The authors question the current approach used in remediai policies which focuses on single target groups of poHuters and individual marker substances. Such an approach does not consider the interactions between species and the possible combined effect of chemical, physical and biological parameters affecting aquatic ecosystems.

D.M.J. TUBBING, D. DE ZWART AND T. BURGER­WIERSMA, (1995) Phytoplankton Dynamics in the River Meuse as Affected by Pollution, in The Netherlands Journal of Aquatic EcoJogy, 29(1), pp. 103-116.

FRANCE

EVALUATION OF PHOSPHORUS FROM POINT SOURCES ON A CATCHMENT

AREA SCALE

Researchers from the Savoie region in France, have proposed a new model for evaluating phosphorus from point sources in a cat ch men t area. The model distinguishes phosphorus coming from the area itself, sources coming from upstream, and diffuse sources. The informat ion collected from the application of the model should contribute to developing and adjusting eutrophication control strategies in sensitive areas.

lt is diffteult, because of the costs invotved, to produce a reliable evaluation of point sources of phosphorus for a large area by measuring the flow from each

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source. The rate of transfer of P originating from upstream is also hard to predict since it depends widely on the hydrofogical and climatic conditions.

Because of these difficulties, a team from INRA (Institut National de Recherche Agronomique) in Thonon, Savoie, France have developed a mode! which aims at evaluating point sources by measuring the P released during droughts, when point sources are likely to be the predominant input of P into rivers and soluble P represents 90% of total P.

Severa! conditions are necessary to guarantee the efficacy of the approach, such as a detailed knowledge of the hydrology of the catchment area and of the variabitity of the P input to the river. ln addition, sampling must be done out of flooding periods since phosphorus reaches the sediment, where it forms an important reservoir of P, likely to be reteased during floods.

During droughts, point sources represent the only significant input of P into the area and their volume is constant, regardless of the hydrotogical and climatic conditions. ln contrast, the volume of diffuse P exported from the area varies with the flow of water. When the water flow increases, the amount of P tends to increase likewise until it reaches a constant value. When this threshold is reached, inputs equal outputs and a reliabte measure of P from point sources can be taken.

This method was tested in the Foron catchment areas, a tributary of the Geneva Lake. Weekly figures were considered to b e the most reliable since concentrations of P from point sources varies hourty and daily. For an area covering 56, 9 km2, the average weekly output of P was estimated at 90 kg.

The authors consider that this approach is applicable to areas with a surface less than 100 J<m2. Any larger than this size, the transfer rate for water becomes too long (more than 24 hours) and the possible error margin is too important for a sampling period of a week.

DORIOZ, J-M. ET ORAND, A. (1996). Evaluation des rejets de pollution ponctuelle de phosphore à l'échelle des bassins versants, in Environnement et Techniques, 153:61-64 (in French)

NEW BOOK

PHOSPHORUS IN THE GLOBAL ENVIRONMENT

Transfers, Cycles and Management

IN EUROPE

3

The Scientific Committee on Problems of the Environment (not to be confused with the organisation SCOPE which edits this newsletter) publishes a compilation of articles o n transfers, cycles a n d man a geme nt of phosphorus i n the environ ment.

Phosphorus in the Global Environment is the achievement of a major study launched by the Scientifte Committee on Problems of the Environment in 1987. lts objective was to improve the understanding of •phosphorus cycles in terrestrial and aquatic ecosystems". Data and research presented during four regional workshops by 240 scientists were summarised during a final workshop hetd in Hungary in 1993.

We quote below a summary of this highly detailed volume as published by the editer:

"Phosphorus is one of the world's vital but retatively scarce resources, which is a limiting factor in plant (and therefore food and fibre) production. This volume brings together data and concepts on the transfer and transformations of phosphorus.

Although the phrase "biogeochemical cycle• is commonly used to describe the tate of elements of the environment, it has become apparent that for phosphorus, linear transfers from land to rivers to lakes and seas are more typical. ln sorne regions, these transfers are augmented by the addition of mined phosphates and manure, and surplus phosphate needs to be managed with care. Environmental managers need to incorporate an understanding of phosphorus transfers into their decision making.

But the contrais on phosphorus transfers through tandscapes are complex, and an integrated approach by terrestrial and aquatic scientists is needed to develop such an understanding. The use of water bodies as sensitive and fragile indicators of phosphorus tosses from surrounding watersheds is an important step towards a comprehensive scientific approach. Processes which limit plant production are often wen understood but socio-economic constraints limit remediation and must form part of a comprehe n sive ap proach t o phosphor u s management ....

TIESSEN, H. (1995) Phosphorus in the Global Environment; Transters, Cycles and Management, in SCOPE n°54, pp460,published by John Wiley & Sons, Chichester. * reproduced with the authorisation of the publisher.

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SWEDEN

IMPACT OF FISH FARMING ON LAKES' PHOSPHORUS CONCENTRATION

An extensive research project has been conducted in Sweden to evaluate the impact of fish farms on eutrophication phenomene in lakes (see also our previous Newsletter). One of the study's objectives was to see w hether phosphorus emissions from rainbow trout farms could be used to reduce mercury and radiocaesium levels in the takes' fish.

However, no result on this issue could be obtained since no i ncrease i n P­concentration had appeared due to fish farming activities. The authors concluded that fish production could be muttiplied by 200 without affecting the lakes' trophic condition.

As part of an extensive study on eutrophication phenomenon in Swectish lakes, a group of scientists at the Uppsala University studied the pôssibility of using phosphorus emissions from fish farms as a way of reducing the high levels of mercury and radiocesium present in the lakes' wild fish {the theory of "biological dilution.") This hypothesis could not be verified since the expected rise in total P­concentration did not occur. Conclusions of previous studies had shown that this lack of correlation between fish farming and P· concentration cannot be explained by climate conditions, precipitation or by the hydrology and the chemistry of the lakes. lnsteacl, the reasons likely to explain these results were:

the uptake of P from trout faeces by wild fish (mainly bream and roach), the elimination of phosphorus from the fish feed b y bio production directly foll owed by sedimentation, predation through the food chain and transter downstream.

Data has also shown that no significant primary production resulted from the activities of the fish farrns, which seems to indicate that direct uptake of phosphate from the lakes by wild fish was very substantial.

4

The authors conclude that environmental authorities shoutd review their methods for evaluation of the impact of fish farming on lakes' eutrophication. ln addition, they suggested that the tonnage presently allowed by farming permits could be raised from 50 tonslyear to 10, 500 tonslyear without affecting the lakes.

HAKANSON, L, CARLSSON, L., JOHANSSON, T. (1995) Gan emissions from fish farms be used as a remedia/ measure for lakes? in Vatten 51: pp 112-124, Lund (in Swedish.)

GERMANY

OPPORTUNITIES AND CONSTRAINTS IN THE RECYCLING OF NUTRIENTS

This article addresses the question of nutrient recycling. Dr. Joachim Lammel, from the Centre for Pla nt Nutrition a nd Environmental Research in Hanninghof, Germany, studies the different components of the recycling nutrients issue (historical, sociological, economical and technical) Several approaches are discussed, particu larly: • Nutrient use and cycling in agriculture • Demand from society for recyling nutrients • Recycling of manure • Recycling of urban waste • Recycling and the fertiliser industry

With the development of intensive farming the traclitional nutrient cycfing practices on-farm are no longer appropriate. ln Europe the boom of mineral fertilisers means that we can now supply growing urban populations, and has broken down traditional nutrient cycling practices. ln order to restore the cycle nutrients need to be used and recycled efficiently. At the sarne time, in many developing countries, mineral ferblisers are necessary to restore nutrient cycling in depleted soils.

Due to intensive livestock farming, manure is now the main source of nutrients available for recycling, and surpluses are becoming increasingly frequent. The efficient management of this source of nutrients is now the challenge for livestock farmers, particularly in the light of possible proposed legislation limiting the use of minerar fertilisers.

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Despite growing public opinion to limit the use of landfill sites the application of urban waste to farmland is not recommended because of the potential content of heavy metals and other harmful substances, unless separate collection of organic waste is implemented. This, however, represents substantial extra costs which may be justified by sustainable arguments such as the saving of landfilf space, or recycling of finite resources {eg. phosphate).

The fertiliser industry is the last key element in this process, as it consumes lïmited resources, such as phosphorus extracted from rock and energy from fossil fuels. tts ïnvolvement in the coming debate between farmers and policy makers will finally contribute to closing the nutrient cycle again.

LAMMEL, J. (1995) Opportunities and Constraint in the Recycling of Nutrients, paper presented at the International Conference in Cambridge, organised by The Fertiliser Society, Proceedings N°372, Peterborough.

AUSTRALIA

A NEW PROCESS REDUCES THE AMOUNT AND COST OF CHEMICALS USED

FOR PHOSPHORUS REMOVAL FROM WASTE WATER.

Alum sludge might contribute to lowering both cost and amount of chemicals used for removing phosphorus from waste water. If the trials conducted by the Centre f or

-- Wastewater Treatment at the University o f New South Wales at Bowral are successful, this technique could be used throughout Australia.

Alum is normally used as a coagulant in drinking water treatment . This proœss generates a by-product, alum sludge, which is left to dry in a pond before going to landfill.

The idea promoted by the Department of Land and Water Conservation and the Co-operative Research Centre for Wast.e Management and Pollution Control consists of reintroducing to waste water the alum sludge from previous treatment.

The main advantage of the alum re-use process which uses the same product twice is a reduction of the amount of chemicals used in the chemical recovery processes. This technique is also reported to be more cast-efficient than Biological Nutrient Removal, a

IN EUROPE

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technique considered expensive for small and medium size wastewater works.

Australian Environmental Review (December 95) Vol. 10, n°11:p.13

NOR WAY

ASSESSMENT OF COST EFFICIENCY AND SUSTAINABILITY OF WASTE WATER

TREATMENT PROCESSES

Cost efficiency and sustainability o f different commonly used waste water treatment techniques were evaluated. Results show that among the methods assessed, chemical treatment alone and advanced treatment with chemical pr• treatment rank first with respect to both criteria. The author notes that municipal waste water treatment equipment is often c ho s en according to n ational or international treatment standards rather than the quality and self purification capacity of the local receiving water.

The evaluation was b ased on a treatment plant designed for serving a population of 100 000 people. Five different treatment process were examined:

Primary (mechanical) treatment Secondary (high load biological or chemical) treatment Advan c e d sec o ndar y w i t h nitrification (mechanicallbiological or chemicaJJbiological) Te rtiary treatment (mech./biol./chem. or chem.lbiol.) Advanced tertiary treatment including nitrogen removal (mech.lbiol./chem., chem.lbiol. or mech.lbiol.)

The cost of the treatment increases with the sophistication of the technology, which in turn depends on the type of component removed from waste water. Therefore, the cost efficiency was cafculated for each single component. For example, secondary treatment and primary precipitation were the most cost efficient techniques with respect to BOD and suspended solids removal respectively. ln tum, chemical treatment by primary precipitation was found to have the best ratio for phosphorus removal. Different possible situations were also considered with respect to the impact of sewage water discharge on receiving waters. A costJimpact ratio was cafculated using the oxvgen consumption potential of each component as weil as the likely impact of P and N on

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algal growth, under both marine and fresh water conditions.

Two methodologies were used to assess the sustainability of each process:

the energy and raw material consumption vs each process' potential to reduce oxygen consumption in receiving waters the lite cycle assessment (LCA) technique, using the SimaPro mode!.

The results show that direct chemical treatment has a better ratio with respect to cost/efficiency, oost/impact and energy consumptionlimpact when compared to

biological treatment. The LCA indicator is also favourable to direct chemical treatment. The study also showed that using the biogas resulting from sludge digestion also represents a viable way to increase the treatment sustainability.

The author concludes that water treatment technologies should be selected in the light of costlbenefit criteria. He regrets that "such analyses are rarely carried out and that suitable tools for such evaluations are lacking". Acknowledging the limits of a study presented as an attempt to show a direction for developing evaluation methods", the author recommends that more work be done on developing a reliable mode! for calculating the . impact under different receiving water conditions.

0DEGAARD, H. (1995) An evaluation of cost efficiency and sustainability of different waste water treatment processes. in Vatten 51:291-299, Lund.

The SCOPE Newsletter is produced by the SCIENTIHC COMMITfEE ON PHOSPHATES IN EUROPE, a non commercial, non profit-making association (hsodation Sans But Lucratif) based in Brussels.

The association includes international groups headquartered in Belgium, France, Spain, Sweden and the UK, producers of a wide variety of detergent ingredients including phosphates. Its aim is to provide a platform for objective and sdenttific information on the effects of phosphate-containing and phosphate-free detergents on the environment.

The SCOPE Newsletter is open to input from its readers across Europe and we welcome ail comments or information. Contributions from readers are in"Vited on all subjects concerning phosphates, detergents, sewage treatment and the environment. You are invited to submit sdentific papers for résumé, to send comments on the studies mentioned in this Newslener or other sdentific or technical news.

For more information, please contact: E.C.U. (European Communications Unit)- who produce this Newsletter for SCOPE -20, rue de l'Arcade, 75008 Paris, France, Tel.+ 33 1 44 94 80 70 Fax +33 1 44 94 81 01 E-mail ecu@net.asi.fr

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NUMBER SEVENTEEN

UNITED KINGDOM �.2

Carp appear to be a major cause of eutrophication in Engllsh sites of special scientiflc lnterest Eutrophie status and symptoms of eutrophication of

_ 1 02 Sites of Special Scientific Inter est in England were examined. Eighty four showed symptoms of eutrophication, a phenomenon attributed primarily to sewage effluent, carp and bream.

SWITZERLAND �.2

The state of Swiss lakes The Swiss Federal Office for the Environment, Forests and Landscape published a review of the environmental state of the country's 20 most important lakes.

FIN LAND �.3

Impact of EDTA on toxicity of metals We publish here below the full text of a letter submitted to SCOPE Newsletter. lt presents the results of a study conducted to evaluate the impact

-- of metal complexation by EDT A on toxicity on Photobacterium phosphoreum.

FIN LAND �.4

Factors influencing the service life of home appliances A study was conducted in Finland for the Consumer Affair Bureau of the Ministry of Trade and lndustry in order to assess the factors influencing the service life of home appliances. As for laundry and dish washing machines, it appears that phosphate free-detergents are responsible for a greater amount of deposit accumulation in the machines than phosphate containing products.

APRIL 1996

SWEDEN �.5

Flows and effects of phosphorus in a lake - calibrations and simulations using the LEEDS model The LEEDS model (Lake Eutrophication, Effect­Dose-Sensitivity model) was used to evaluate the actual impact of fish-farming on Lake Bullaren, Sweden. After calibrating, the multi-criteria model was used to predict the maximum volume of phytoplankton likely to result from the input and circulation of phosphorus. lt appears that a significant part of the variability is related to internai dynamic processes and that over-simplistic models such as vollenweider or OECD-type can give totally meaningless predictions.

THE NETHERLANDS �.6

Selection mechanisms controlling blomass distribution Water, Science & Technology published a compilation of the papers presented in a conference on Selection Mechanisms Controlling Biomass Distribution between Cyanobacteria, Phytoplankton and Macrophytes Species, held in Noordwijkerhout, The Netherlands, in December 1994.

CANADA �.6

Autumn leaves gathering in urban areas may contribute to eutrophication Leaves piled up along roadsides in urban centres may contribute to up to 5 % of the total export of phosphorus from urban catchment. Prompt leaf pickup is recommended in order to prevent aggravation of eutrophication phenomenon.

SC OPE is a non-commercial, non-profit ma king European association based in Brussels.

lts aim is to provide a platform for objective and scientific information on the effects of phosphate·containing and phosphate·free detergents on the environment.

SCOPE NEWSLETIER fJroduced by European Communications Unit- 81, rue François Mermet- 69160 TASSIN - FRANCE -Tél. (33) 78 34 23 39

SCOPE : Scientific Committee on Phosphates in Europe ·Association Sans But Lucratif sise à Bruxelles et soumise à la Loi du 27 juin 1921

UNITED KINGDOM

CARP APPEAR TO BE A MAJOR CAUSE OF EUTROPHICATION IN ENGLISH SITES

OF SPECIAL SCIENTIFIC INTEREST

Eutrophie status and symptoms of eutrophicat ion of 102 Sites of Special Sc ient ific lnterest in England w ere examined. Eighty four showed symptoms of eutrophication, a phenomenon attributed primarily to sewage effluent, carp and bream.

The concept of Site of Special Scientific lnterest (SSSI) was initiated by English Nature in order to allow a better understanding and assessment of state and degree of changes of aquatic sites of particular importance. After collecting data from English Nature, the National River Authority, British Waterways, water supply companies and field sampling, the study went on to examine the trophic state and eutrophication symptoms of 1 02 selected SSSis.

Of ali these sites, 84 % showed symptoms of eutrophication. The occurence of this phenomenon had changed the conservation interest of the site in 69 cases.

Table 1. Number of SSSis showinf�oms of eutro�Wcation OEGDGategory Numbêro s SS sWHh

Ohgotroptîtc tv'esotrophtc

Eutrophie Hypertrophie Unknown

Total

examined symptoms of

� eulr�ication

13 9 13 10 ffi 57 9 9

102 85

Among the 85 sites affected, untreated sewage effluent discharge was identified as the primary cause of eutrophication in 35 cases, and possibly in 5 additional cases. The second most important cause was the presence of certain tish , mainly common carp and common bream.

These species search for food in the sediment. ln so

doing, they mobilise nutrients and increase the water body's turbidity. ln fifteen cases, external nutrient load appeared unlikely to lead to the symptoms

observed. lt is only the presence of large carp (Cyprinus carpio) which could explain the appearance of eutrophication problems.

ln sorne sites, the additional presence of bream (Abramis brama) also c o ntributed to the phenomenon. Apart from the feeding in the sediment, this last species is known tor feeding on zooplankton during the first year of lite, which has a direct impact on phytoplankton grazing and regulation.

The symptoms of deterioration were observed mainly among the plant communities. The authors mention, however, that this may simply be due to the tact that plants are more frequently monitored than animal communities.

The authors recommend that :

sewage effluent be diverted or treated with phosphate removal in at least 30 cases, biomanipulative measures including carp removal be implemented in 18 cases, systematic monitoring of SSSis for the effect of eutrophication be carried out.

L. Carvalho, B. Moss, The current status of a sample of English Sites of Special Scientific lnterest subject to eutrophication. in Aquatic Conservation: Marine and Freshwater Ecosystems, Vol. 5, 191-204, 1995.

SWITZERLA ND

THE STATE OF SWISS LAKES

The Sw iss Fe deral Office f or t he Environment, Forests and Landscape publlshed a review of the environmental state of the country's 20 most Important lakes.

This document is devided into 3 parts, one containing a review of basic limnology principles, one addressing the question of waste water treatment, protection and rehabilitation of lakes and the last one presenting the 20 lakes, with respect to their environmental status.

2

SCIENTIFIC

COMMITTEE

ON PHOSPHATES

SCOPE NEWSLETTER

The chapter on limnology devotes a large part to the question of thermal exchanges, lake stratification and to the role of nutrients. As an illustration of the complexity of these processes, the report describes how excessive consumption of oxygen from deep waters. due to enhanced primary production in surface layers, can trigger chemical reactions in the sediment which, in turn, provokes an important release of phosphorus.

The report discusses protection and remediation measures applied in Switzerland. Phosphorus removal from waste water by simultaneous precipitation was made mandatory in ali waste water treatment (WWT) plants of lakes catchment areas in 1971. Sorne WWT plants located in the most s e n s i t i v e a r e a s a r e eq u i p p e d w i t h

- flocculationffiltration systems which allow a 90% phosphate recovery efficiency.

The report indicates that the amount of phosphorus in domestic waste water before treatment was reduced by 30% after the introduction of a detergent phosphate ban in 1986.

Despite the measures implemented, it is concluded that, because of the high amounts of P present in the sediment, a return to the "natural" state is often impossible by simply reducing the nutrient input to the lakes, even when conditions are favourable. ln most cases, internai measures such as deep water recirculation, introduction of low nutrient containing water and oxygenation are necessary to prevent P release from the lake beds.

The Swiss lakes are divided into 3 groups:

Oligotrophic lakes with a phosphorus concentration between 3 and 30t�QPII. At these concentrations, the oxygen present in deep waters and sediment is abundant enough to effectively transfer P from water to the sediment.

Lakes with a medium to heavy P load, with a concentration between 30 and 60JJgP/I. P concentrations in these lakes have been decreasing due to remediai measures in their catchment areas.

Lake Leman and Zurich belong to this group. Their upper layer of water, where primary production occurs, is low in phosphorus content when compared to the lowest layer. Although a

IN EUROPE

complete mixing of the lake water is very unlikely to happen due to the lakes' morphology, major climatic change could provoke this mixing and increase the presence of nutrients in the phototrophic layer.

Very heavily loaded lakes with a phosphorus concentration between 90 to 140JJgP/I. They belong to areas with a very high population concentration or intensive farming. ln this last case, it is very unlikely that the lakes will rapidly move towards the second group.

As a conclusion, the authors consider that the environmental status of the Swiss lakes has greatly improved since the seventies but acknowledge that P reduction measures did not always reach the set objectives. Agriculture is now considered the major source of pollution. T hey also warn about the likely adverse consequences of a long term warming of the lakes' temperatures.

Office Fédéral de l'Environnement, des Forêts et du Paysage, L'Etat des Lacs Suisses, Cahier de l'Environnement no 237, Berne, 1994.

FIN LAN D

IMPACT OF EDTA ON TOXICITY OF METALS

We publish here below the full text of a letter submitted to SCOPE Newsletter. lt presents the results of a study conducted to evaluate t h e impact of metal complexation by EDTA on toxicity on Photobacterium phosphoreum.

Among a number of industrial applications, Ethylenedimineacetic acid (EDT A) is used as an additive to substitute for polyphosphate in cleaning formulations. ln external waste treatment, it is known for having a low reduction capacity and for increasing heavy metal concentration in waste water effluents by forming cyclic, water-soluble chelates with metal ions. Th us, a high percentage of EDT A is released into natural waters.

3

Association Sans But Lucratif

As a nitrogen containing compound, EDT A might constitute a source of nutrient for aquatic algae under certain circumstances. EDTA also increases general permeability, releasing calcium ions from cell membranes.

The presence of EDT A was monitored in pristine waters of Central Europe. Concentrations between 1-80 pg/1 were found, which are not likely to cause acute taxie effects. On the ether hand very little is known of the long-term toxicity of EDT A.

ln this study, the toxicity of several heavy metals was investigated after complexation by EDTA. Microtox bioassay, based on measuring the bioluminescence of Photobacterium phosphoreum, was used as an indication of toxicity. The reproducibility of data revealed correlation coefficients between O. 983-1.000.

The results suggest that complexation by this chelating agent increases the toxicity of iron, has very low or no influence on the toxicity of Cu, Cd and Hg, and reduces noticeably the toxicity of Zn and Pb. The slopes of the dose-response curves were steeper for metal complexes than for metals, suggesting that toxicity mechanisms change during complexation.

The inhibitory effect of EDT A on metal toxicity is explained by the binding of the reactive sites of heavy metal ions, thus preventing their normal action.

Mika Sillanpaa, Letter submitted to SCOPE NEWSLETTER, Laboratory of lnorganic and Analytical Chemistry , Helsink i University of Technology, January 1996.

FINLAND

FACTORS INFLUENCING THE SERVICE LIFE OF HOME APPLIANCES

A study was conducted in Finland for the Consumer Affair Bureau of the Ministry o f Trade and lndustry in order to assess the factors influencing the service life of home appliances.

4

As for laundry and dish washing machines, lt appears that phosphate free-detergents are responsible for a greater amount of deposit accumulation in the machines than phosphate containing products.

The trial involving the comparison of phosphate­containing and phosphate-free detergent started after a questionnaire distributed to appliance repairmen revealed that faults in washing machines had increased after the introduction of phosphate­free products.

The tests were conducted in 4 separate districts corresponding to water hardnesses ranging from 2°dH to 7°dH. Two hundred washes were done, which corresponds to a year's use. The assessment of the impact on washing machines was performed by a service expert group, in the presence of representatives of detergent companies.

The trials showed that the use of P-free detergents increases the level of encrustation on beth dish and laundry washing machines.

Furthermore, with dishwashers, a film was formed on the surface of the dishes when P-free detergents were used. This did not occur with phosphate containing brands.

As for laundry washing machines, tests showed a slightly higher in-machine deposition with P-free products but the difference with P-containing cnes was not as marked as for dishwashers. The most obvious precipitation appeared in the drain hose.

lt is stated that more tests are needed to reach a final conclusion since only one kind of washing machine was used and a limited number of detergents were tested. However, these results clearly suggest that beth the type of builder and the water hardness influence the number of problems in washing machines and dishwashers.

A Reisbacka, A Rytkonen, Factors influencinq the service /ife of home appliances, work carried out by the Working Efficiency lnstitute (Fin/and) for the Ministry of Trade and lndustry, TTS-Jnstitutes publication 34111995, ISBN 951-788-3, 245 p., 1995.

SCIENTIFIC

COMMITIEE

ON PHOSPHATES

SCOPE NEWSLETTER

S WEDE N

FLOWS AND EFFECTS OF PHOSPHO RUS IN A LAKE - CALIBRATIONS AND

SIMULATIONS USING THE LEEDS MODEL

The LEEDS model (Lake Eutrophication, Effect-Dose-Sensltlvity model) was used to evaluate the actual Impact of fish-farming o n L ake Bullaren, S weden. After callbrating, the multi-criteria model was used to predict the maximum volume of phytoplankton likely to result from the input and circulation of phosphorus. lt appears that a slgniflcant part of the variabillty is related to Internai dynamic processes and that slmplistic modela auch as Vollenweider or OECD-type can give totally meaningless predictions.

Lake Bullaren is in the middle of a controversy related to the possible impact of fish farming on the trophic status of the lake. The LEEDS model is presented as "time dependent, generic-dynamic model which accounts for ali major processes regulating the distribution and effects of phosphorus in lakes.

ln order to calibrate the model, data were gathered on amounts, fluxes and concentrations of phosphorus in the lake. From this step on, predictions of the maximum volume of phytoplankton (target effect variable) were made on a monthly basis.

Dissolved and particulate P, stratification, sedimentation, re-suspension/advection, diffusion, bioturb ation, predation, fishing, mixing and mineralisation are among the parameters accounted for by the LEEDS model, as weil as the different P sources feeding the lake.

The study focused primarily on providing:

the quantification of internal loading,

a phosphorus budget (amounts and fluxes),

indications on the effects of seasonal variations on the input of P,

IN EUROPE

a new format for environmental consequences analysis, with special attention to the volume of phytoplankton and extreme climatic conditions,

a better understanding of the processes regulating recovery after an hypothetical extreme eutrophication.

Among the results of the study, it appears that:

About 5 % of the P contained in the active surface of the sediment - which accounts for 90% of the P in the lake - is transported each year to the productive surface waters.

Of the three primary phosphorus inputs, 72% cornes from the in-flowing waters (natural P-flow and agriculture), 25% from the fish farm and the remairiing 3% from the rain.

The exchange of phosphorus through sedimentation, r esuspe nsion and diffusion is very extensive. The P flow from the sediment corresponds to almost half the total weight of P externat input.

Lake Bullaren could probably tolerate a fish production of 1 000 tons a year, white the present permit allows only 70 t/year.

tt is suggested that the controversy surrounding fish farming activities on Lake Bullaren are based on an over-simplistic understanding of phytoplankton regulation phenomenon derived from the application of models such as Vollenweider or OECD-types, qualified as very crude and not adapted to a case like Lake Bull aren.

L. Hakanson, L. Carlsson, Flows and effects of phosphorus- Calibration and simulations usinq the LEEDS-mode/ in Lake Bullaren, Sweden, Vatten 51, 183-218, Lund 1995.

5

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THE NETHERLANDS

SELECTION MECHANISMS CONTROLLING BIOMASS DISTRIBUTION

Water, Science & Technology publlshed a compilation of the papers presented in a conference on Selection Mechanlsms Controlling Biomass Distribution between Cya n o bacteria, Phyto p lankton and Ma c r o p hyt e s S p e c i e s, h e ld in Noordwijkerhout, The Netherlands, in December 1994.

This conference paid particular attention to the changes occurring in the phototrophic compartment of aquatic ecosystems. The conference was organised by the International Association for Water Quality and the International Association of Theoretical and Applied Limnology. ln total, 82 scientists from 19 countries participated in this conference.

37 papers were presented covering 5 separate fields:

Light Climate and Hydrodynamics Nutrients Physical and Chemical Factors Biological Interactions Physical, Chemical and Biological Interactions.

The conference confirmed that the mechanisms of the major ecological factors influencing competition and succession are weil known and that the understanding of the contribution of each factor is rapidly growing.

The conference has also demonstrated that strategies focused on reduction of external nutrient alone are often not sufficient enough to restore eutrophied waters and that an integrated approach is necessary.

ln this approach, biological and physicochemical factors must be accounted for in order to enable more balanced water management practices. Stronger co-operation between technologists and biologists is also recommended.

L.R.Mur, P.M. V isser and H. Rei th, Selection Mechanisms Controllinq Biomass Distribution. introductory paper by C. Reynolds, in Water Science & Technology, Vol. 32, N°4, 1995.

CANADA

AUTUMN LEAVES GATHERING IN URBAN AREAS MAY CONTRIBUTE TO

E UTR OPHICATION

Leaves plled up along roadsides in urban centres may contribute to up to 5 % of the total export of phosphorus from urban catchment. Prompt l eaf pickup is rec ommended in order to. prevent a ggr a v a t i o n o f eutrophication phenomenon.

Laboratory experiments were conducted by the Department of Biology at McGill University, Montreal, to evaluate the amount of phosphorus exported by water leaching through birch and trembling aspen leaves.

ln southern Canada, plant litter represents from 200 to 800g/m2, a possibly significant nutrient supply to receiving waters. The amount of P exported to gutters and rivers can be substantial depending on the length of the period between leaf gathering and pickup.

The objective of this study was to assess the amou nt of total phosphorus released per g of dried and non­dried leaves placed in flasks containing distilled water.

Analysis of samples extracted from the flasks after one week showed a strong linear relation between P release and leaf mass. Based on average litter fall in southern Canada, it is estimated that fallen leaves can contribute 11 to 45 mg of total P per m2, which represents up to 5% of the total export of total P from urban areas.

No significant difference was observed between total P concentrations of samples from dried and non­dried leaves.

6

SCIENT! FIC COMMITIEE

ON PHOSPHATES

SCOPE NEWSLETTER IN EUROPE

H. Guibert, R. France, Laboratory Prediction of

Phosphorus Release from Deciduous Leaves to

Urban Runoff, Water Quality Res. J. Canada, Vol. 30,

N°2, 243-246, 1995.

The SCOPE Newsletter is produced by the SCIENTIFIC COMMITTEE ON PHOSPHATES IN EUROPE, a non commercial, non proflt­maklng association (Association Sans But Lucratif) based in Brussels.

The11SS0Ciation lncludes international groups headquartered in Belgium, France, Spain, Sweden and the UK, producers of a wlde variety of detergent ingredients including phosphates. lts aim ls to provide a platform for objective and sclentifiC Information on the effects of phosphate-containing and phosphate-free detergents on the environment.

The SCOPE Newsletter is open to input from its readers across Europe and we welcome ali comments or information. Contributions from readers are invited on ali subjects conceming phosphates, detergents, sewage treatment and the environment. Vou are invited to submit scientifiC papers for résumé, to send comments on the studies mentioned in this Newsletter or other scientifiC or technical news.

For each study or paper mentioned in the SCOPE Newsletter, the full document can be obtained directly from :

E.C.U. (European Communications Unit)- who produce this Newsletter for SCOPE-81, rue FranÇOis Mermet- 69160 TASSIN France- Tél: (33) 78.34.23.39- Fax: (33) 78. 34. 83. 49

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���-�------------------------�S�C�IE

�NrrTrriFlfiC

�-------- -------------------COMMITTEE

ON PHOSPHATES

SCOPE NEWSLETTER IN EUROPE

Number Sixteen

SC ANDIN AVI A p.2

Revision Of The Nordic Environmental Label

Three years after the adoption of its first version, the revised Nordic Swan Label is m o r e s e v e r e o n m o s t detergents' components, but reverses its earlier position on phosphates. Completely excluded in the 1992 ver s i on, phosphate containing detergents can now apply for and obtain the Nordic environmental label.

SWEDEN

Swedish Water Treatment Experts Compare Phosphate-Based And Phosphate-Free Products

p.3

"The use of phosphate based detergents means lower organic loading, lower ecotoxicity to micro organisms, lower concentration of suspended solids and a lower oxygen consumption in municipal sewage treatment plant"-

No vern ber 1995

This statement was made i n a report published b y VA-FORSK, a research programme managed by VAV, the Swedish Water Association. The report is entitled: Laundry detergents: Effects on waste water treatment and the environment,

UNITED KINGDOM p.S

Phosphates Used To Restore Acidified Lakes

Tests conducted by researchers at the lnstitute of Freshwater Ecology and Lancaster University reveal that phosphates can be used to control lake acidity.

FRANCE & SWITZERLAND �.6

Evolution Of Phosphorus And Biomass Concentration ln Lake Geneva.

Both phosphorus and biomass concentrations decreased in 1994. Biomass concentration still remains higher than values recorded from 1989 to 1991. The International Commission for the Protection of the Leman Waters (CIPEL) announces that 87 % of the· population of the lake's catchment area is now connected to waste water treatment plants.

SCOPE 1s a non-commercial, non-profit making European association based m Brussels.

lts aim 1s to provide a platform for objective and sc1ent1fic mformat1on on the effects of phosphate-contaming and phosphate-free detergents on the environment

SCOPE NEWSLETTER

produced by European Communications Unit- 81, rue François Mermet- 69160 TASSIN - FRANCE -Tél. (33) 78 34 23 39

SCOPE : Scientific Committee on Phosphates in Europe -Association Sans But Lucratif sise à Bruxelles et soumise à la Loi du 27 juin 1921

------- ------

SCAN DINA VIA

REVISION OF THE NORDIC

ENVIRONMENTAL LABEL

Three years after the adoption of its

first version, the revised Nordic Swan

Label is more severe on m ost

detergents' components, but reverses

its earlier position on phosphates.

Completely excluded in the 1992

v e r s i o n , phosphate containing

detergents can now apply for and

obtain the Nordic environmental label.

After the revision of the Nordic environmental

label, applicable in the Spring of 1996, only

about half the products already labelled will

pass the new criteria.

T o the Swedish Standards Institution

(Standardiseringen i Sverige - SIS), which is

responsible for developing the Nordic Swan

for household laundry detergents, the idea

behind the label, presented as an educational

instrument, is to encourage manufacturers to

formulate increasingly environmentally sound

products. Today, 84 % of the Swedish

consumers favour Swan-labelled products.

2

The two other environmental labels used in

scandinavia also allow a certain amount of

phosphate in detergents.

The new criteria for household laundry

detergents cover more parameters and ali the

ingredients are assessed. The volume of

zeolites, a phosphate substitute, is now taken

into account.

-.

�

Requirements on dosage and efficiency are

also established. The Swedish National

Board for Consumer Policies produced a test

method for measuring washing efficiency at

the recommended dosage.

Phosphates reassessed

"We have reassessed the issue of

phosphates", sa ys Magnus Hedenmark, eco­

toxicologist at SIS. This assessment led to

the decision that " a detergent can have the

Swan ecolabel and contain a certain amount

of phosphate".

The decision by SIS follows the position

adopted by the European Commission, which

also allows phosphate containing products to

apply for the recently adopted European

Ecolabel for household laundry detergents.

SCIENT! FIC

COMMITTEE

ON PHOSPHATES

SCOPE NEWSLETTER

The first version of the Nordic label excluded

ali phosphate containing detergents. Back in

1992, this decision had provoked reactions

fr om water treatment authorities and

associations like the Swedish Nature

Conservation Society, which disagreed with

the exclusion of phosphates.

The Swan label applies to products sold in

Finland, lceland, Norway and Sweden.

Eco-/abe/ling of detergents for textiles, Criteria

document 1992103194 - 1999104104, Version

3, SIS Miljomarkning, SIS-Standardiseringen

i Sverige, P. O. Box 3295, S-1 03 66"

Stockholm., Sweden.

SWEDEN

S WEDI SH W ATER TRE ATMENT

EXPERT S COMPARE PHO SPH AT&

BA SED AND PHO SPHATE-FREE

PRODUCT S

"T he use of phosphate based

detergents means lower organlc

loading, lower ecotoxicity to micro

organisms, lower concentration of

suspended solids and a lower oxygen

IN EUROPE

3

consumption i n municipal sewage

treatment plant "

This statement was made in a report

published by V A-FOR SK, a research

programme managed by V AV, the

Swedish Water Association. The report

is entitled: Laundry detergents: Effects

on waste water treatment and the

environment,

Water samples from 27 household laundry

detergents were tested in order to evaluate

the chemical parameters and the toxicity of

each product. The detergents were divided

into 3 groups, depending on the builder

system used :

- phosphate based powder detergents,

- phosphate-free powder detergents,

- liquid detergents without phosphates.

The study cornes to the following conclusions:

Suspended solids

The concentration of suspended solids is on

average 10 times higher in the effluents of

phosphate-free products than in phosphate

based detergents (see fig. 1 ) . The use of

phosphate substitutes leads to the production

of larger amounts of sewage sludge, which

Association Sans But Lucratif

must be disposed of by incineration or in

landfill sites.

1500

1000 1--

500 !--- !---

� hfffL fi l"i n 1-:i

PBD PFP PFL 0

fig. 1 : Suspended solids (mg/1)

ln contrast, phosphate is the only detergent

builder which can be recovered in sewage

plants and recycled, therefore increasing the

possible exploitation of this resource. On the

other hand, the use of phosphate leads to

larger consumption of flocculating agents in

sewage treatment, when enhanced biological

treatment is not applied.

Concentration of organic material and

ecotoxicity

Phosphate based detergents produce the

effluent with the lowest concentration of

organic material (measured in TOC (see fig.

2) and OOC1). The release of organic

material leads to a consumption of oxygen

(BOO) in the effluent from the washing

machine three times higher when phosphate-

l TOC and DOC stand for Total Organic Carbon and Dissolved Organic Carbon.

4

free powders are used instead of phosphate

based powders. The Biological Oxygen

Oemand (BOO) is six times higher when

phosphate-free liquid detergents are used

(see fig. 3).

1000

800

600

400

200

0

3000

2500

2000

1500

1000

500

0

t"

� PBD PFP

fig. 2: Total Organic carbon (mg/1)

�

""�"'l"'

rrrrn 1 PBP 1 PFP

l"'

� fig. 3 : Biological Oxygen Demand (mg/1)

PFL

"'

--·

PFL

The ecotoxicity towards micro-organisms

generally follows the content of organic

carbon (TOC). Therefore, there are large

differences between the detergents tested.

Liquid detergents without phosphates appear

to have the highest potential impact, with

respect to this parameter (see fig. 4).

SCIENT! FIC

COMMIITEE

ON PHOSPHATES

SCOPE NEWSLETTER IN EUROPE

500

400

300

200

100

0

909

..,.. �.mm Fi

770

1-

,.

fi - -

., 1 PSP 1 LSP

fig. 4 : Ecotoxicity (measured according to the microtox method) LC50 (15 min.)

No long term environmental impact

The report notes "that most ecolabeled

products are easily degradable". Among the

products tested, none or very little ecotoxicity

could be detected after 14 days of

degradation, with the exception of one

product which is no longer on the market.

The potential ecotoxicity will rapidly disappear

as the surfactant degrades, and the risk of any

long term environmental effects will be

eliminated, says the report.

The study was conducted assuming that

advanced w aste water trea tment is

implemented. Therefore, no assessment is

made of the possible environmental impact of

ecotoxicity, when sewage water is discharged

directly into the natural environment.

5

Cajsa Wahlberg, VAV- VA-Forsk, Tvattmedel

- effecter pa reningsverk och mi/jo, Stockholm

Vatten, 1995.

UNITED KINGDOM

PHOSPHATES USED TO RESTORE

ACIDIFIED LAKES

Tests conducted by researchers at the

lnstitute of Freshwater Ecology and

Lancaster University reve_al t h at

phosphates can be used to control

lake acidity.

A series of tests were conducted from 1992 to

1993 in Seathwaite tarn, in Northern England

Lake District, in order to determine the ability

of. phosphate fertilisation to control lake

acidity. Many lakes are dramatically acidified

by airborne p ollutants generated by

combustion from industrial and transportation

activities.

The traditionnal approach to lake acidification

consists of adding lime to lower the pH value

of the water. This technique, however, tends

to provoke a modification of the plant and

animal communities naturally present in the

lakes. The original species are often unable to

Association Sans But Lucratif

cope with the excessive concentration of

calcium and are rapidly replaced by more

tolerant species, thus modifying the natural

composition of the ecosystems.

The idea of using phosphates to control lake

acidity is supported by the tact that

phytoplankton productivity can act as an

important butter of soft water. The

phytoplankton feeds on nitrate ions which are

largely responsible for lake acidity.

The experiment showed that the phosphorus

added to the lake in the form of fertiliser is

rapidly assimilated by growing phytoplankton.

For each mole of phosphate, 16 moles of

nitrate nitrogen are consumed. This ratio

illustrates that very low quantities of fertiliser

are needed to obtain satisfactory results in

terms of pH increase without affecting the

community structure.

The corresponding increase of phytoplankton

chlorophyll was due to " the rapid growth of

small species that are commonly referred to

as nano-plankton".

ln turn, "these species are consumed in large

numbers by tiller-feeding crustacean which

greatly accelerate the rate at which the fixed

carbon is deposited in fixed sediments.

6

The authors conclude that "phosphate can

have beneficiai effects within the environment,

and that the complete elimination may

enhance problems of low productivity and

acidity.

W. Da vison, O. G. George & N. J. A. Edwards,

Contra/led reversai of lake acidifcation by

treatment with phosphate fertilizer, in Nature,

vol. 317, october 1995.

FRANCE & SWITZERLAND

EVOLUTION OF PHOSPHORUS AND

BIOMASS CONCENTRATION IN LAKE

GENEVA.

8o t h ph o sph o rus and biomass

concentrations d ecre ased in 1994.

Biomass concentration still remains

higher than values recorded from 1989

to 1991. The International C ommission

for the Protection of the Leman Waters

(CIPEL) announces that 87 o/o of the

population of the lake's catchment

area is now connected to waste water

treatment plants.

SCIENTIFIC

COMMITTEE

ON PHOSPHATES

SCOPE NEWSLETTER

Phosphorus content of the Lake has regularly

decreased since 1981, to reach a 45

m icrograms per l i tre concentration.

Meanw h i l e, however, the biomass

concentration has not followed a regular

decreasing curve.

As of in 1989, the biomass stopped

decreasing. lnstead, the period from 1989 to

1993 showed an unexpected increase of

phytoplankton density. During the latest year

of observations, biomass had decreased

again but was still higher than the lowest

value reached in 1989.

ln the light of this data, it is difficult to define

whether the evolution of the biomass during

the last year is part of a decreasing trend, or if

it must be considered as an exception in a

general stabilisation of the Lake's

phytoplankton density.

The regular decrease in phosphorus

concentration is the result of an extensive

p h osphorus control programme. This

programme includes:

-the installation of waste water treatment

for almost the entire population

surrounding the lake (85%),

- the control of phosphorus release by

industries,

IN EUROPE

7

- the closing or modification of pig farms,

- the increase of storage facilities for

manure produced by cattle farms.

The changes observed in the lake

phytoplankton show that eutrophication and

related negative effects are diminishing. This

evolution, however is still considered

insufficient.

1994 primary productivity is regarded as quite

low. The very low value registered during the

spring is thought to be due to a very short

period of sunshine.

Rapport sur les études et recherches

entreprises dans Je bassin lém anique,

Campagne 1994, Consei l Scientifique de la

Commission Internationale pour la Protection

des Eaux du Léman, 1995.

Association Sans But Lucratif

The SCOPE Newsletter ls produced by the SCIENTIFIC COMMITTEE ON PHOSPHATES IN EUROPE, a non commercial, non profit­making association (Association Sans But Lucratif) based in Brussels.

The association lncludes International groups headquartered ln Belgium, France, Spain, Sweden and the UK, producers of a wide variety of detergent ingredients including phosphates. lts aim ls to provlde a platform for objective and scientific information on the effects of phosphate-containing and phosphate-free detergents on the environment.

The SCOPE Newsletter ls open to input from its readers across Europe and we welcome ali comments or information. Contributions from readers are invited on ali subjects conceming phosphates, detergents, sewage treatment and the environment. You are invited to submit scientific papers for résumé, to send comments on the studies mentioned in this Newsletter or other scientific or

technical news.

For each study or paper mentioned in the SCOPE Newsletter, the full document can be obtained directly from :

E.C.U. (European Communications Unit)- who produce this Newsletter for SCOPE-81, rue François Mermet- 69160 TASSIN France- Tél : (33) 78.M.23.39- Fax L(33) 78. 34. 83. 49

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